UI Development (JavaScript-compatible Web-like Development Paradigm) Overview
The JavaScript-compatible web-like development paradigm uses the classical three-stage programming model, in which HML is used for building layouts, CSS for defining styles, and JavaScript for adding processing logic. UI components are associated with data through one-way data-binding. This means that when data changes, the UI automatically updates with the new data. This development paradigm has a low learning curve for frontend web developers, allowing them to quickly transform existing web applications into ArkUI applications. It could be helpful if you are developing small- and medium-sized applications with simple UIs.
For details about the components to support better application development, see the JavaScript-compatible Web-like Development Paradigm APIs.
Overall Architecture
ArkUI with the JavaScript-compatible web-like development paradigm consists of the following layers: application layer, frontend framework layer, engine layer, and porting layer.

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Application Layer
Contains applications with FAs you developed. The FA application in this document refers to the application with FAs developed using JavaScript.
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Framework Layer
Parses UI pages and provides the Model-View-ViewModel (MVVM), page routing, custom components and more for front end development.
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Engine Layer
Implements animation parsing, Document Object Model (DOM) building, layout computing, rendering command building and drawing, and event management.
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Porting Layer
Abstracts the platform layer to provide abstract APIs to connect to the platform. For example, event interconnection, rendering pipeline interconnection, and lifecycle interconnection.