@ohos.fastbuffer (FastBuffer)

A FastBuffer object is a more efficient buffer container for representing a byte sequence of a fixed length. It is used to store binary data.

When the FastBuffer object is constructed using from, only the parameters of the FastBuffer, Uint8Array, string, Array, and ArrayBuffer types are supported.

FastBuffer is recommended if high-performance processing of large binary data (such as images, file transfer, and network communication) is required.

NOTE

The initial APIs of this module are supported since API version 20. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Container classes, implemented in static languages, have restrictions on storage locations and properties, and do not support custom properties or methods.

Modules to Import

import { fastbuffer } from '@kit.ArkTS';

BufferEncoding

type BufferEncoding = 'ascii' | 'utf8' | 'utf-8' | 'utf16le' | 'ucs2' | 'ucs-2' | 'base64' | 'base64url' | 'latin1' | 'binary' | 'hex'

Enumerates the supported encoding formats.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Type	Description
'ascii'	ASCII format.
'utf8'	UTF-8 format.
'utf-8'	UTF-8 format.
'utf16le'	UTF-16LE format.
'ucs2'	Alias of UTF-16LE.
'ucs-2'	Alias of UTF-16LE.
'base64'	Base64 format.
'base64url'	Base64URL format.
'latin1'	Alias of iso-8859-1, which is backward compatible with the ASCII format.
'binary'	Binary format.
'hex'	Hexadecimal format.

fastbuffer.alloc

alloc(size: number, fill?: string | FastBuffer | number, encoding?: BufferEncoding): FastBuffer

Creates and initializes a FastBuffer object of the specified length.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
size	number	Yes	Size of the FastBuffer object to create, in bytes. Value range: 0 <= size <= UINT32_MAX
fill	string | FastBuffer | number	No	Value to be filled in the buffer. The default value is 0.
encoding	BufferEncoding	No	Encoding format (valid only when fill is a string). The default value is 'utf8'. If an unrecognized encoding format is passed, TypeError is thrown.

Return value

Type	Description
FastBuffer	FastBuffer object created.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.alloc(5);
let buf2 = fastbuffer.alloc(5, 'a');
let buf3 = fastbuffer.alloc(11, 'aGVsbG8gd29ybGQ=', 'base64');
console.info(buf2.toString());
// Output: aaaaa
console.info(buf3.toString());
// Output: hello world

fastbuffer.allocUninitializedFromPool

allocUninitializedFromPool(size: number): FastBuffer

Creates an uninitialized FastBuffer object of a specified size from the buffer pool. You need to use fill to initialize the FastBuffer object created.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
size	number	Yes	Size of the FastBuffer object to create, in bytes. Value range: 0 <= size <= UINT32_MAX

Return value

Type	Description
FastBuffer	Uninitialized FastBuffer object.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(10);
buf.fill(0);
// "buf":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

fastbuffer.allocUninitialized

allocUninitialized(size: number): FastBuffer

Creates an uninitialized FastBuffer object of a specified size. You need to use fill to initialize the FastBuffer object created.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
size	number	Yes	Size of the FastBuffer object to create, in bytes. Value range: 0 <= size <= UINT32_MAX

Return value

Type	Description
FastBuffer	Uninitialized FastBuffer object.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitialized(10);
buf.fill(0);
// "buf":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

fastbuffer.byteLength

byteLength(value: string | FastBuffer | TypedArray | DataView | ArrayBuffer | SharedArrayBuffer, encoding?: BufferEncoding): number

Obtains the number of bytes of a string based on the encoding format.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	string | FastBuffer | TypedArray | DataView | ArrayBuffer | SharedArrayBuffer	Yes	Target string.
encoding	BufferEncoding	No	Encoding format. The default value is 'utf8'. If an unrecognized encoding format is passed, TypeError is thrown.

Return value

Type	Description
number	Number of bytes of the string.

Example

import { fastbuffer } from '@kit.ArkTS';

let str = 'hello world';
console.info(`${str}: ${str.length} characters, ${fastbuffer.byteLength(str, 'utf-8')} bytes`);
// Output: hello world: 11 characters, 11 bytes

str = '\u00bd + \u00bc = \u00be';
console.info(`${str}: ${str.length} characters, ${fastbuffer.byteLength(str, 'utf-8')} bytes`);
// Output: ½ + ¼ = ¾: 9 characters, 12 bytes

fastbuffer.compare

compare(buf1: FastBuffer | Uint8Array, buf2: FastBuffer | Uint8Array): -1 | 0 | 1

Compares two FastBuffer objects. This API is used for sorting FastBuffer objects.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
buf1	FastBuffer | Uint8Array	Yes	First object to compare.
buf2	FastBuffer | Uint8Array	Yes	Second object to compare.

Return value

Type	Description
-1 | 0 | 1	Returns 0 if buf1 is the same as buf2. Returns 1 if buf1 comes after buf2 when sorted. Returns -1 if buf1 comes before buf2 when sorted.

Error codes

For details about the error codes, see Universal Error Codes.

ID	Error Message
10200068	The underlying ArrayBuffer is null or detach.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.from('1234');
let buf2 = fastbuffer.from('0123');
let res = fastbuffer.compare(buf1, buf2);

console.info(Number(res).toString());
// Output: 1

fastbuffer.concat

concat(list: FastBuffer[] | Uint8Array[], totalLength?: number): FastBuffer

Copies the content of a specified byte length from an array to a new FastBuffer object and returns the concatenated FastBuffer object.

If the total length of all objects in the array exceeds totalLength, the length of the returned result will be truncated to totalLength.

If the total length of all objects in the array is less than totalLength, the excess part of the returned result will be padded with zeros.

System capability: SystemCapability.Utils.Lang

Atomic service API: This API can be used in atomic services since API version 20.

Parameters

Name	Type	Mandatory	Description
list	FastBuffer[] | Uint8Array[]	Yes	Array of objects to concatenate.
totalLength	number	No	Total length of bytes to be copied. The default value is 0.

Return value

Type	Description
FastBuffer	FastBuffer object created.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	Range error. Possible causes: The value of the parameter is not within the specified range.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.from("1234");
let buf2 = fastbuffer.from("abcd");
let buf = fastbuffer.concat([buf1, buf2]);
console.info(buf.toString('hex'));
// Output: 3132333461626364

fastbuffer.from

from(array: number[]): FastBuffer

Creates a FastBuffer object with the specified array.

System capability: SystemCapability.Utils.Lang

Atomic service API: This API can be used in atomic services since API version 20.

Parameters

Name	Type	Mandatory	Description
array	number[]	Yes	Array to create a FastBuffer object.

Return value

Type	Description
FastBuffer	FastBuffer object created.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0x62, 0x75, 0x66, 0x66, 0x65, 0x72]);
console.info(buf.toString('hex'));
// Output: 627566666572

fastbuffer.from

from(arrayBuffer: ArrayBuffer | SharedArrayBuffer, byteOffset?: number, length?: number): FastBuffer

Creates a FastBuffer object of the specified length that shares memory with ArrayBuffer.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
arrayBuffer	ArrayBuffer | SharedArrayBuffer	Yes	Target object.
byteOffset	number	No	Byte offset. The default value is 0.
length	number	No	Length of the FastBuffer object to create, in bytes. The default value is arrayBuffer.byteLength minus byteOffset. Value range: 0 <= length <= arrayBuffer.byteLength - byteOffset

Return value

Type	Description
FastBuffer	FastBuffer object created.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	Range error. Possible causes: The value of the parameter is not within the specified range.
10200068	The underlying ArrayBuffer is null or detach.

Example

import { fastbuffer } from '@kit.ArkTS';

let ab = new ArrayBuffer(10);
let buf = fastbuffer.from(ab, 0, 2);
console.info(buf.length.toString());
// Output: 2

fastbuffer.from

from(buffer: FastBuffer | Uint8Array): FastBuffer

Copies the data of a passed FastBuffer object to create a FastBuffer object and returns the new one.

Creates a FastBuffer object based on the memory of a passed Uint8Array object and returns the new object, maintaining the memory association of the data.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
buffer	FastBuffer | Uint8Array	Yes	Target object.

Return value

Type	Description
FastBuffer	FastBuffer object created.

Error codes

For details about the error codes, see Universal Error Codes.

ID	Error Message
10200068	The underlying ArrayBuffer is null or detach.

Example

import { fastbuffer } from '@kit.ArkTS';

// Create a FastBuffer object of the FastBuffer type.
let buf1 = fastbuffer.from('buffer');
let buf2 = fastbuffer.from(buf1);
console.info(buf2.toString());
// Output: buffer

// Create a FastBuffer object of the Uint8Array type to ensure memory sharing between objects.
let uint8Array = new Uint8Array(10);
let buf3 = fastbuffer.from(uint8Array);
buf3.fill(1)
console.info("uint8Array:", uint8Array)
// Output: 1,1,1,1,1,1,1,1,1,1

fastbuffer.from

from(value: string, encoding?: BufferEncoding): FastBuffer

Creates a FastBuffer object based on a string in the given encoding format.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	string	Yes	String.
encoding	BufferEncoding	No	Encoding format. The default value is 'utf8'. If an unrecognized encoding format is passed, TypeError is thrown.

Return value

Type	Description
FastBuffer	FastBuffer object created.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.from('this is a test');
let buf2 = fastbuffer.from('7468697320697320612074c3a97374', 'hex');

console.info(buf1.toString());
// Output: this is a test
console.info(buf2.toString());
// Output: this is a tést

fastbuffer.isBuffer

isBuffer(obj: Object): boolean

Checks whether the specified object is a FastBuffer object.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
obj	Object	Yes	Object to check.

Return value

Type	Description
boolean	Check result. The value true is returned if the object is a FastBuffer object; otherwise, false is returned.

Example

import { fastbuffer } from '@kit.ArkTS';

let result = fastbuffer.isBuffer(fastbuffer.alloc(10)); // 10: fastbuffer size
console.info("result = " + result);
// Output: result = true
let result1 = fastbuffer.isBuffer(fastbuffer.from('foo'));
console.info("result1 = " + result1);
// Output: result1 = true
let result2 = fastbuffer.isBuffer('a string');
console.info("result2 = " + result2);
// Output: result2 = false
let result3 = fastbuffer.isBuffer([]);
console.info("result3 = " + result3);
// Output: result3 = false
let result4 = fastbuffer.isBuffer(new Uint8Array(1024));
console.info("result4 = " + result4);
// Output: result4 = false

fastbuffer.isEncoding

isEncoding(encoding: string): boolean

Checks whether the encoding format is supported.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
encoding	string	Yes	Encoding format.

Return value

Type	Description
boolean	Check result. The value true is returned if the encoding format is supported; otherwise, false is returned.

Example

import { fastbuffer } from '@kit.ArkTS';

console.info(fastbuffer.isEncoding('utf-8').toString());
// Output: true
console.info(fastbuffer.isEncoding('hex').toString());
// Output: true
console.info(fastbuffer.isEncoding('utf/8').toString());
// Output: false
console.info(fastbuffer.isEncoding('').toString());
// Output: false

fastbuffer.transcode

transcode(source: FastBuffer | Uint8Array, fromEnc: string, toEnc: string): FastBuffer

Transcodes a FastBuffer or Uint8Array object from one encoding format to another.

This API supports the following encoding formats: 'ascii', 'utf8', 'utf16le', 'ucs2', 'latin1', and 'binary'.

System capability: SystemCapability.Utils.Lang

Atomic service API: This API can be used in atomic services since API version 20.

Parameters

Name	Type	Mandatory	Description
source	FastBuffer | Uint8Array	Yes	Target object.
fromEnc	string	Yes	Current encoding format. For details about the supported formats, see BufferEncoding.
toEnc	string	Yes	Target encoding format. For details about the supported formats, see BufferEncoding.

Return value

Type	Description
FastBuffer	New FastBuffer object in the target encoding format.

Example

import { fastbuffer } from '@kit.ArkTS';

let newBuf = fastbuffer.transcode(fastbuffer.from('buffer'), 'utf-8', 'ascii');
console.info("newBuf = " + newBuf.toString('ascii'));
// Output: newBuf = buffer

FastBuffer

Properties

System capability: SystemCapability.Utils.Lang

Atomic service API: This API can be used in atomic services since API version 20.

Name	Type	Read-Only	Optional	Description
length	number	Yes	No	Length of the FastBuffer object, in bytes.
buffer	ArrayBuffer	Yes	No	ArrayBuffer object.
byteOffset	number	Yes	No	Offset of the FastBuffer object in the memory pool.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from("1236");
console.info(JSON.stringify(buf.length));
// Output: 4
let arrayBuffer = buf.buffer;
console.info(JSON.stringify(new Uint8Array(arrayBuffer)));
// Output: {"0":49,"1":50,"2":51,"3":54}
console.info(JSON.stringify(buf.byteOffset));
// Output: 0

compare

compare(target: FastBuffer | Uint8Array, targetStart?: number, targetEnd?: number, sourceStart?: number, sourceEnd?: number): -1 | 0 | 1

Compares the current this object with the target object and returns the comparison result.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
target	FastBuffer | Uint8Array	Yes	Target FastBuffer object to compare.
targetStart	number	No	Offset to the start of the data to compare in the target FastBuffer object. The default value is 0. Value range: 0 <= targetStart <= target.length
targetEnd	number	No	Offset to the end of the data to compare in the target FastBuffer object (not inclusive). The default value is the length of the target FastBuffer object. Value range: 0 <= targetEnd <= target.length
sourceStart	number	No	Offset to the start of the data to compare in this FastBuffer object. The default value is 0. Value range: 0 <= sourceStart <= this.length
sourceEnd	number	No	Offset to the end of the data to compare in this FastBuffer object (not inclusive). The default value is the length of this FastBuffer object. Value range: 0 <= sourceEnd <= this.length

Return value

Type	Description
-1 | 0 | 1	Comparison result. -1: This object comes before the target object when sorted. 0: The two objects are the same. 1: This object comes after the target object when sorted.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	Range error. Possible causes: The value of the parameter is not within the specified range.
10200068	The underlying ArrayBuffer is null or detach.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.from([1, 2, 3, 4, 5, 6, 7, 8, 9]);
let buf2 = fastbuffer.from([5, 6, 7, 8, 9, 1, 2, 3, 4]);

console.info(buf1.compare(buf2, 5, 9, 0, 4).toString());
// Output: 0
console.info(buf1.compare(buf2, 0, 6, 4).toString());
// Output: -1
console.info(buf1.compare(buf2, 5, 6, 5).toString());
// Output: 1

copy

copy(target: FastBuffer| Uint8Array, targetStart?: number, sourceStart?: number, sourceEnd?: number): number

Copies data at the specified position in this FastBuffer object to the specified position in another FastBuffer object.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
target	FastBuffer | Uint8Array	Yes	FastBuffer or Uint8Array object to which data is copied.
targetStart	number	No	Offset to the start position in the target object where data is copied. The default value is 0. Value range: 0 <= targetStart <= UINT32_MAX
sourceStart	number	No	Offset to the start position in this FastBuffer object where data is copied. The default value is 0. Value range: 0 <= sourceStart <= UINT32_MAX
sourceEnd	number	No	Offset to the end position in this FastBuffer object (not inclusive). The default value is the length of this FastBuffer object. Value range: 0 <= sourceEnd <= this.length

Return value

Type	Description
number	Total length of the data copied, in bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	Range error. Possible causes: The value of the parameter is not within the specified range.
10200068	The underlying ArrayBuffer is null or detach.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.allocUninitializedFromPool(26);
let buf2 = fastbuffer.allocUninitializedFromPool(26).fill('!');

for (let i = 0; i < 26; i++) {
  buf1.writeInt8(i + 97, i);
}

buf1.copy(buf2, 8, 16, 20);
console.info(buf2.toString('ascii', 0, 25));
// Output: !!!!!!!!qrst!!!!!!!!!!!!!

entries

entries(): IterableIterator<[number, number]>

Creates and returns an iterator that contains key-value pairs of this FastBuffer object.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
IterableIterator<[number, number]>	Iterator that contains the key and value, both of which are of the number type.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from('buffer');
let pair = buf.entries();
let next: IteratorResult<Object[]> = pair.next();
while (!next.done) {
  console.info("fastbuffer: " + next.value);
  /*
  Output: buffer: 0,98
           fastbuffer: 1,117
           fastbuffer: 2,102
           fastbuffer: 3,102
           fastbuffer: 4,101
           fastbuffer: 5,114
  */
  next = pair.next();
}

equals

equals(otherBuffer: Uint8Array | FastBuffer): boolean

Checks whether this FastBuffer object is the same as another FastBuffer object.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
otherBuffer	Uint8Array | FastBuffer	Yes	FastBuffer object to compare.

Return value

Type	Description
boolean	Check result. The value true is returned if the two objects are equal byte by byte; otherwise, false is returned.

Error codes

For details about the error codes, see Universal Error Codes.

ID	Error Message
10200068	The underlying ArrayBuffer is null or detach.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.from('ABC');
let buf2 = fastbuffer.from('414243', 'hex');
let buf3 = fastbuffer.from('ABCD');

console.info(buf1.equals(buf2).toString());
// Output: true
console.info(buf1.equals(buf3).toString());
// Output: false

fill

fill(value: string | FastBuffer | Uint8Array | number, offset?: number, end?: number, encoding?: BufferEncoding): FastBuffer

Fills this FastBuffer object at the specified position. By default, data is filled cyclically.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	string | FastBuffer | Uint8Array | number	Yes	Value to fill.
offset	number	No	Offset to the start position in this FastBuffer object where data is filled. The default value is 0. Value range: 0 <= offset <= this.length
end	number	No	Offset to the end position in this FastBuffer object (not inclusive). The default value is the length of this FastBuffer object. Value range: 0 <= end <= this.length
encoding	BufferEncoding	No	Encoding format (valid only when value is a string). The default value is 'utf8'. If an unrecognized encoding format is passed, TypeError is thrown.

Return value

Type	Description
FastBuffer	FastBuffer object filled with the specified value.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	Range error. Possible causes: The value of the parameter is not within the specified range.
10200068	The underlying ArrayBuffer is null or detach.

Example

import { fastbuffer } from '@kit.ArkTS';

let b = fastbuffer.allocUninitializedFromPool(50).fill('h');
console.info(b.toString());
// Output: hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh

includes

includes(value: string | number | FastBuffer | Uint8Array, byteOffset?: number, encoding?: BufferEncoding): boolean

Checks whether this FastBuffer object contains the specified value.

If byteOffset is a positive number, the offset is calculated from 0. If byteOffset is a negative number, the offset is calculated from the end.

If byteOffset is greater than or equal to this.length, false is returned. If byteOffset is less than or equal to -this.length, the system checks whether the value exists in the entire FastBuffer.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	string | number | FastBuffer | Uint8Array	Yes	Value to match.
byteOffset	number	No	Number of bytes to skip before starting to check data. If byteOffset is a positive number, the offset is calculated from 0. If byteOffset is a negative number, the offset is calculated from the end. The default value is 0.
encoding	BufferEncoding	No	Encoding format (valid only when value is a string). The default value is 'utf8'. If an unrecognized encoding format is passed, TypeError is thrown.

Return value

Type	Description
boolean	Check result. The value true is returned if the object contains the specified value; otherwise, false is returned.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from('this is a buffer');
console.info(buf.includes('this').toString());
// Output: true
console.info(buf.includes('be').toString());
// Output: false

indexOf

indexOf(value: string | number | FastBuffer | Uint8Array, byteOffset?: number, encoding?: BufferEncoding): number

Obtains the index of the first occurrence of the specified value in this FastBuffer object. If no match is found, -1 is returned.

If byteOffset is a positive number, the offset is calculated from 0. If byteOffset is a negative number, the offset is calculated from the end.

If byteOffset is greater than or equal to this.length, -1 is returned. If byteOffset is less than or equal to -this.length, the index of the first occurrence of the specified value in the FastBuffer is returned.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	string | number | FastBuffer | Uint8Array	Yes	Value to match.
byteOffset	number	No	Number of bytes to skip before starting to check data. If byteOffset is a positive number, the offset is calculated from 0. If byteOffset is a negative number, the offset is calculated from the end. The default value is 0.
encoding	BufferEncoding	No	Encoding format (valid only when value is a string). The default value is 'utf8'. If an unrecognized encoding format is passed, TypeError is thrown.

Return value

Type	Description
number	Index obtained.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from('this is a buffer');
console.info(buf.indexOf('this').toString());
// Output: 0
console.info(buf.indexOf('is').toString());
// Output: 2

keys

keys(): IterableIterator<number>

Iterator created.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
IterableIterator<number>	Iterator created.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from('buffer');
let keys = buf.keys();
for (const key of keys) {
  console.info(key.toString());
}
/*
Output: 0
        1
        2
        3
        4
        5
*/

values

values(): IterableIterator<number>

Creates and returns an iterator that contains the values of this FastBuffer object.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
IterableIterator<number>	Iterator.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.from('buffer');
let pair = buf1.values()
let next:IteratorResult<number> = pair.next()
while (!next.done) {
  console.info(next.value.toString());
  /*
  Output: 98
           117
           102
           102
           101
           114
  */
  next = pair.next();
}

lastIndexOf

lastIndexOf(value: string | number | FastBuffer | Uint8Array, byteOffset?: number, encoding?: BufferEncoding): number

Obtains the index of the last occurrence of the specified value in this FastBuffer object. If no match is found, -1 is returned.

If byteOffset is a positive number, the offset is calculated from 0. If byteOffset is a negative number, the offset is calculated from the end.

If byteOffset is greater than or equal to this.length, the index of the last occurrence of the specified value in the FastBuffer is returned. If byteOffset is less than or equal to this.length, -1 is returned.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	string | number | FastBuffer | Uint8Array	Yes	Value to match.
byteOffset	number	No	Number of bytes to skip before starting to check data. If byteOffset is a positive number, the offset is calculated from 0. If byteOffset is a negative number, the offset is calculated from the end. The default value is this.length - 1.
encoding	BufferEncoding	No	Encoding format (valid only when value is a string). The default value is 'utf8'.

Return value

Type	Description
number	Index obtained.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from('this buffer is a buffer');
console.info(buf.lastIndexOf('this').toString());
// Output: 0
console.info(buf.lastIndexOf('buffer').toString());
// Output: 17

readBigInt64BE

readBigInt64BE(offset?: number): bigint

Reads a 64-bit, big-endian, signed big integer from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 8

Return value

Type	Description
bigint	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 8. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x70,
  0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78]);
console.info(buf.readBigInt64BE(0).toString());
// Output: 7161960797921896816

readBigInt64LE

readBigInt64LE(offset?: number): bigint

Reads a 64-bit, little-endian, signed big integer from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 8

Return value

Type	Description
bigint	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 8. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x70,
  0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78]);
console.info(buf.readBigInt64LE(0).toString());
// Output: 8100120198111388771

readBigUInt64BE

readBigUInt64BE(offset?: number): bigint

Reads a 64-bit, big-endian, unsigned big integer from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 8

Return value

Type	Description
bigint	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 8. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x70,
  0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78]);
console.info(buf.readBigUInt64BE(0).toString());
// Output: 7161960797921896816

readBigUInt64LE

readBigUInt64LE(offset?: number): bigint

Reads a 64-bit, little-endian, unsigned big integer from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 8

Return value

Type	Description
bigint	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 8. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x70,
  0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78]);
console.info(buf.readBigUInt64LE(0).toString());
// Output: 8100120198111388771

readDoubleBE

readDoubleBE(offset?: number): number

Reads a 64-bit, big-endian, double-precision floating-point number from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 8

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 8. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([1, 2, 3, 4, 5, 6, 7, 8]);
console.info(buf.readDoubleBE(0).toString());
// Output: 8.20788039913184e-304

readDoubleLE

readDoubleLE(offset?: number): number

Reads a 64-bit, little-endian, double-precision floating-point number from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 8

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 8. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([1, 2, 3, 4, 5, 6, 7, 8]);
console.info(buf.readDoubleLE(0).toString());
// Output: 5.447603722011605e-270

readFloatBE

readFloatBE(offset?: number): number

Reads a 32-bit, big-endian, single-precision floating-point number from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 4

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 4. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([1, 2, 3, 4, 5, 6, 7, 8]);
console.info(buf.readFloatBE(0).toString());
// Output: 2.387939260590663e-38

readFloatLE

readFloatLE(offset?: number): number

Reads a 32-bit, little-endian, single-precision floating-point number from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 4

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 4. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([1, 2, 3, 4, 5, 6, 7, 8]);
console.info(buf.readFloatLE(0).toString());
// Output: 1.539989614439558e-36

readInt8

readInt8(offset?: number): number

Reads an 8-bit signed integer from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 1

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 1. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([-1, 5]);
console.info(buf.readInt8(0).toString());
// Output: -1
console.info(buf.readInt8(1).toString());
// Output: 5

readInt16BE

readInt16BE(offset?: number): number

Reads a 16-bit, big-endian, signed integer from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 2

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 2. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0, 5]);
console.info(buf.readInt16BE(0).toString());
// Output: 5

readInt16LE

readInt16LE(offset?: number): number

Reads a 16-bit, little-endian, signed integer from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 2

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 2. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0, 5]);
console.info(buf.readInt16LE(0).toString());
// Output: 1280

readInt32BE

readInt32BE(offset?: number): number

Reads a 32-bit, big-endian, signed integer from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 4

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 4. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0, 0, 0, 5]);
console.info(buf.readInt32BE(0).toString());
// Output: 5

readInt32LE

readInt32LE(offset?: number): number

Reads a 32-bit, little-endian, signed integer from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 4

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 4. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0, 0, 0, 5]);
console.info(buf.readInt32LE(0).toString());
// Output: 83886080

readIntBE

readIntBE(offset: number, byteLength: number): number

Reads the specified number of bytes from this FastBuffer object at the specified offset, and interprets the result as a big-endian, two's complement signed value that supports up to 48 bits of precision.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	Yes	Offset. The default value is 0. Value range: 0 <= offset <= this.length - byteLength
byteLength	number	Yes	Number of bytes to read. Value range: 1 <= byteLength <= 6

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from("ab");
let num = buf.readIntBE(0, 1);
console.info(num.toString());
// Output: 97

readIntLE

readIntLE(offset: number, byteLength: number): number

Reads the specified number of bytes from this FastBuffer object at the specified offset and interprets the result as a little-endian, two's complement signed value that supports up to 48 bits of precision.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	Yes	Offset. The default value is 0. Value range: 0 <= offset <= this.length - byteLength
byteLength	number	Yes	Number of bytes to read. Value range: 1 <= byteLength <= 6

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);
console.info(buf.readIntLE(0, 6).toString(16));
// Output: -546f87a9cbee

readUInt8

readUInt8(offset?: number): number

Reads an 8-bit unsigned integer from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 1

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 1. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([1, -2]);
console.info(buf.readUInt8(0).toString());
// Output: 1
console.info(buf.readUInt8(1).toString());
// Output: 254

readUInt16BE

readUInt16BE(offset?: number): number

Reads a 16-bit, big-endian, unsigned integer from this FastBuffer object at the specified offset.

System capability: SystemCapability.Utils.Lang

Atomic service API: This API can be used in atomic services since API version 20.

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 2

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 2. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0x12, 0x34, 0x56]);
console.info(buf.readUInt16BE(0).toString(16));
// Output: 1234
console.info(buf.readUInt16BE(1).toString(16));
// Output: 3456

readUInt16LE

readUInt16LE(offset?: number): number

Reads a 16-bit, little-endian, unsigned integer from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 2

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 2. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0x12, 0x34, 0x56]);
console.info(buf.readUInt16LE(0).toString(16));
// Output: 3412
console.info(buf.readUInt16LE(1).toString(16));
// Output: 5634

readUInt32BE

readUInt32BE(offset?: number): number

Reads a 32-bit, big-endian, unsigned integer from this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 4

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 4. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0x12, 0x34, 0x56, 0x78]);
console.info(buf.readUInt32BE(0).toString(16));
// Output: 12345678

readUInt32LE

readUInt32LE(offset?: number): number

Reads a 32-bit, little-endian, unsigned integer from this FastBuffer object at the specified offset.

System capability: SystemCapability.Utils.Lang

Atomic service API: This API can be used in atomic services since API version 20.

Parameters

Name	Type	Mandatory	Description
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 4

Return value

Type	Description
number	Data read.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 4. Received value is: [offset].

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0x12, 0x34, 0x56, 0x78]);
console.info(buf.readUInt32LE(0).toString(16));
// Output: 78563412

readUIntBE

readUIntBE(offset: number, byteLength: number): number

Reads the specified number of bytes from this FastBuffer object at the specified offset, and interprets the result as an unsigned, big-endian integer that supports up to 48 bits of precision.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	Yes	Offset. The default value is 0. Value range: 0 <= offset <= this.length - byteLength
byteLength	number	Yes	Number of bytes to read. Value range: 1 <= byteLength <= 6

Return value

Type	Description
number	Data read. If the offset is a decimal, undefined is returned.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);
console.info(buf.readUIntBE(0, 6).toString(16));
// Output: 1234567890ab

readUIntLE

readUIntLE(offset: number, byteLength: number): number

Reads the specified number of bytes from this FastBuffer object at the specified offset, and interprets the result as an unsigned, little-endian integer that supports up to 48 bits of precision.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
offset	number	Yes	Offset. The default value is 0. Value range: 0 <= offset <= this.length - byteLength
byteLength	number	Yes	Number of bytes to read. Value range: 1 <= byteLength <= 6

Return value

Type	Description
number	Data read. If the offset is a decimal, undefined is returned.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);
console.info(buf.readUIntLE(0, 6).toString(16));
// Output: ab9078563412

subarray

subarray(start?: number, end?: number): FastBuffer

Truncates this FastBuffer object from the specified position to create a FastBuffer object.

System capability: SystemCapability.Utils.Lang

Atomic service API: This API can be used in atomic services since API version 20.

Parameters

Name	Type	Mandatory	Description
start	number	No	Offset to the start position in this FastBuffer object where data is truncated. The default value is 0.
end	number	No	Offset to the end position in this FastBuffer object (not inclusive). The default value is the length of this FastBuffer object. Value range: start <= end <= this.length

Return value

Type	Description
FastBuffer	FastBuffer object created.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.allocUninitializedFromPool(26);

for (let i = 0; i < 26; i++) {
  buf1.writeInt8(i + 97, i);
}
const buf2 = buf1.subarray(0, 3);
console.info(buf2.toString('ascii', 0, buf2.length));
// Output: abc

swap16

swap16(): FastBuffer

Converts this FastBuffer object into an array of unsigned 16-bit integers and swaps the byte order in place.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
FastBuffer	FastBuffer object swapped.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200009	The fastbuffer size must be a multiple of 16-bits.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);
console.info(buf1.toString('hex'));
// Output: 0102030405060708
buf1.swap16();
console.info(buf1.toString('hex'));
// Output: 0201040306050807

swap32

swap32(): FastBuffer

Converts this FastBuffer object into an array of unsigned 32-bit integers and swaps the byte order in place.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
FastBuffer	FastBuffer object swapped.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200009	The fastbuffer size must be a multiple of 32-bits.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);
console.info(buf1.toString('hex'));
// Output: 0102030405060708
buf1.swap32();
console.info(buf1.toString('hex'));
// Output: 0403020108070605

swap64

swap64(): FastBuffer

Converts this FastBuffer object into an array of unsigned 64-bit integers and swaps the byte order in place.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
FastBuffer	FastBuffer object swapped.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200009	The fastbuffer size must be a multiple of 64-bits.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);
console.info(buf1.toString('hex'));
// Output: 0102030405060708
buf1.swap64();
console.info(buf1.toString('hex'));
// Output: 0807060504030201

toJSON

toJSON(): Object

Converts this FastBuffer object into a JSON object.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
Object	JSON object.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.from([0x1, 0x2, 0x3, 0x4, 0x5]);
let obj = buf1.toJSON();
console.info(JSON.stringify(obj));
// Output: {"type":"FastBuffer","data":[1,2,3,4,5]}

toString

toString(encoding?: string, start?: number, end?: number): string

Converts the data at the specified position in this FastBuffer object into a string in the specified encoding format.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
encoding	string	No	Encoding format (valid only when value is a string). The default value is 'utf8'.
start	number	No	Offset to the start position of the data to convert. The default value is 0.
end	number	No	Offset to the end position of the data to convert. The default value is Buffer.length.

Return value

Type	Description
string	String. When the value of start is greater than or equal to this.length or start is greater than end, an empty string is returned.

Error codes

For details about the error codes, see Universal Error Codes.

ID	Error Message
10200068	The underlying ArrayBuffer is null or detach.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf1 = fastbuffer.allocUninitializedFromPool(26);
for (let i = 0; i < 26; i++) {
  buf1.writeInt8(i + 97, i);
}
console.info(buf1.toString('utf-8'));
// Output: abcdefghijklmnopqrstuvwxyz

write

write(str: string, offset?: number, length?: number, encoding?: string): number

Writes a string of the specified length to this FastBuffer object at the specified position in the given encoding format.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
str	string	Yes	String to write.
offset	number	No	Offset. The default value is 0.
length	number	No	Maximum number of bytes to write. The default value is this.length - offset.
encoding	string	No	Encoding format of the string. The default value is 'utf8'.

Return value

Type	Description
number	Number of bytes written.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	Range error. Possible causes: The value of the parameter is not within the specified range.
10200068	The underlying ArrayBuffer is null or detach.

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.alloc(256);
let len = buf.write('\u00bd + \u00bc = \u00be', 0);
console.info(`${len} bytes: ${buf.toString('utf-8', 0, len)}`);
// Output: 12 bytes: ½ + ¼ = ¾

let buffer1 = fastbuffer.alloc(10);
let length = buffer1.write('abcd', 8);
console.info("length = " + length);
// Output: length = 2

writeBigInt64BE

writeBigInt64BE(value: bigint, offset?: number): number

Writes a 64-bit, big-endian, signed big integer to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	bigint	Yes	Data to write. Value range: -INT64_MAX <= value <= INT64_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 8

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(8);
let result = buf.writeBigInt64BE(BigInt(0x0102030405060708), 0);
console.info("result = " + result);
// Output: result = 8

writeBigInt64LE

writeBigInt64LE(value: bigint, offset?: number): number

Writes a 64-bit, little-endian, signed big integer to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	bigint	Yes	Data to write. Value range: -INT64_MAX <= value <= INT64_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 8

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(8);
let result = buf.writeBigInt64LE(BigInt(0x0102030405060708), 0);
console.info("result = " + result);
// Output: result = 8

writeBigUInt64BE

writeBigUInt64BE(value: bigint, offset?: number): number

Atomic service API: This API can be used in atomic services since API version 20.

Writes a 64-bit, big-endian, unsigned big integer to this FastBuffer object at the specified offset.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	bigint	Yes	Data to write. Value range: 0 <= value <= UINT64_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 8

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(8);
let result = buf.writeBigUInt64BE(BigInt(0xdecafafecacefade), 0);
console.info("result = " + result);
// Output: result = 8

writeBigUInt64LE

writeBigUInt64LE(value: bigint, offset?: number): number

Writes a 64-bit, little-endian, unsigned big integer to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	bigint	Yes	Data to write. Value range: 0 <= value <= UINT64_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 8

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(8);
let result = buf.writeBigUInt64LE(BigInt(0xdecafafecacefade), 0);
console.info("result = " + result);
// Output: result = 8

writeDoubleBE

writeDoubleBE(value: number, offset?: number): number

Writes a 64-bit, big-endian, double-precision floating-point number to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: -DOUBLE_MAX <= value <= DOUBLE_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 8

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 8. Received value is: [offset]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(8);
let result = buf.writeDoubleBE(123.456, 0);
console.info("result = " + result);
// Output: result = 8

writeDoubleLE

writeDoubleLE(value: number, offset?: number): number

Writes a 64-bit, little-endian, double-precision floating-point number to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: -DOUBLE_MAX <= value <= DOUBLE_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 8

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 8. Received value is: [offset]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(8);
let result = buf.writeDoubleLE(123.456, 0);
console.info("result = " + result);
// Output: result = 8

writeFloatBE

writeFloatBE(value: number, offset?: number): number

Writes a 32-bit, big-endian, single-precision floating-point number to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: -FLOAT_MAX <= value <= FLOAT_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 4

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 4. Received value is: [offset]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(8);
let result = buf.writeFloatBE(3.1415, 0);
console.info("result = " + result);
// Output: result = 4

writeFloatLE

writeFloatLE(value: number, offset?: number): number

Writes a 32-bit, little-endian, single-precision floating-point number to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: -FLOAT_MAX <= value <= FLOAT_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 4

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "offset" is out of range. It must be >= 0 and <= buf.length - 4. Received value is: [offset]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(8);
let result = buf.writeFloatLE(3.1415, 0);
console.info("result = " + result);
// Output: result = 4

writeInt8

writeInt8(value: number, offset?: number): number

Writes an 8-bit signed integer to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: -INT8_MAX <= value <= INT8_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 1

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(2);
let result = buf.writeInt8(2, 0);
console.info("result = " + result);
// Output: result = 1
let result1 = buf.writeInt8(-2, 1);
console.info("result1 = " + result1);
// Output: result1 = 2

writeInt16BE

writeInt16BE(value: number, offset?: number): number

Writes a 16-bit, big-endian, signed integer to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: -INT16_MAX <= value <= INT16_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 2

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(2);
let result = buf.writeInt16BE(0x0102, 0);
console.info("result = " + result);
// Output: result = 2

writeInt16LE

writeInt16LE(value: number, offset?: number): number

Writes a 16-bit, little-endian, signed integer to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: -INT16_MAX <= value <= INT16_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 2

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(2);
let result = buf.writeInt16LE(0x0304, 0);
console.info("result = " + result);
// Output: result = 2

writeInt32BE

writeInt32BE(value: number, offset?: number): number

Writes a 32-bit, big-endian, signed integer to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: -INT32_MAX <= value <= INT32_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 4

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(4);
let result = buf.writeInt32BE(0x01020304, 0);
console.info("result = " + result);
// Output: result = 4

writeInt32LE

writeInt32LE(value: number, offset?: number): number

Writes a 32-bit, little-endian, signed integer to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: -INT32_MAX <= value <= INT32_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 4

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(4);
let result = buf.writeInt32LE(0x05060708, 0);
console.info("result = " + result);
// Output: result = 4

writeIntBE

writeIntBE(value: number, offset: number, byteLength: number): number

Writes a big-endian signed value of the specified length to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. The value range depends on byteLength.
offset	number	Yes	Offset. The default value is 0. Value range: 0 <= offset <= this.length - byteLength
byteLength	number	Yes	Number of bytes to write.

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(6);
let result = buf.writeIntBE(0x1234567890ab, 0, 6);
console.info("result = " + result);
// Output: result = 6

writeIntLE

writeIntLE(value: number, offset: number, byteLength: number): number

Writes a little-endian signed value of the specified length to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. The value range depends on byteLength.
offset	number	Yes	Offset. The default value is 0. Value range: 0 <= offset <= this.length - byteLength
byteLength	number	Yes	Number of bytes to write.

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(6);
let result = buf.writeIntLE(0x1234567890ab, 0, 6);
console.info("result = " + result);
// Output: result = 6

writeUInt8

writeUInt8(value: number, offset?: number): number

Writes an 8-bit unsigned integer to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: 0 <= value <= UINT8_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 1

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(4);
let result = buf.writeUInt8(0x3, 0);
console.info("result = " + result);
// Output: result = 1
let result1 = buf.writeUInt8(0x4, 1);
console.info("result1 = " + result1);
// Output: result1 = 2
let result2 = buf.writeUInt8(0x23, 2);
console.info("result2 = " + result2);
// Output: result2 = 3
let result3 = buf.writeUInt8(0x42, 3);
console.info("result3 = " + result3);
// Output: result3 = 4

writeUInt16BE

writeUInt16BE(value: number, offset?: number): number

Writes a 16-bit, big-endian, unsigned integer to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: 0 <= value <= UINT16_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 2

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(4);
let result = buf.writeUInt16BE(0xdead, 0);
console.info("result = " + result);
// Output: result = 2
let result1 = buf.writeUInt16BE(0xbeef, 2);
console.info("result1 = " + result1);
// Output: result1 = 4

writeUInt16LE

writeUInt16LE(value: number, offset?: number): number

Writes a 16-bit, little-endian, unsigned integer to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: 0 <= value <= UINT16_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 2

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(4);
let result = buf.writeUInt16LE(0xdead, 0);
console.info("result = " + result);
// Output: result = 2
let result1 = buf.writeUInt16LE(0xbeef, 2);
console.info("result1 = " + result1);
// Output: result1 = 4

writeUInt32BE

writeUInt32BE(value: number, offset?: number): number

Writes a 32-bit, big-endian, unsigned integer to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: 0 <= value <= UINT32_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 4

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(4);
let result = buf.writeUInt32BE(0xfeedface, 0);
console.info("result = " + result);
// Output: result = 4

writeUInt32LE

writeUInt32LE(value: number, offset?: number): number

Writes a 32-bit, little-endian, unsigned integer to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. Value range: 0 <= value <= UINT32_MAX
offset	number	No	Offset. The default value is 0. Value range: 0 <= offset <= this.length - 4

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(4);
let result = buf.writeUInt32LE(0xfeedface, 0);
console.info("result = " + result);
// Output: result = 4

writeUIntBE

writeUIntBE(value: number, offset: number, byteLength: number): number

Writes an unsigned big-endian value of the specified length to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. The value range depends on byteLength.
offset	number	Yes	Offset. The default value is 0. Value range: 0 <= offset <= this.length - byteLength
byteLength	number	Yes	Number of bytes to write.

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(6);
let result = buf.writeUIntBE(0x1234567890ab, 0, 6);
console.info("result = " + result);
// Output: result = 6

writeUIntLE

writeUIntLE(value: number, offset: number, byteLength: number): number

Writes an unsigned little-endian value of the specified length to this FastBuffer object at the specified offset.

Atomic service API: This API can be used in atomic services since API version 20.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
value	number	Yes	Data to write. The value range depends on byteLength.
offset	number	Yes	Offset. The default value is 0. Value range: 0 <= offset <= this.length - byteLength
byteLength	number	Yes	Number of bytes to write.

Return value

Type	Description
number	Offset plus the number of written bytes.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
10200001	The value of "[param]" is out of range. It must be >= [left range] and <= [right range]. Received value is: [param]

Example

import { fastbuffer } from '@kit.ArkTS';

let buf = fastbuffer.allocUninitializedFromPool(6);
let result = buf.writeUIntLE(0x1234567890ab, 0, 6);
console.info("result = " + result);
// Output: result = 6