JavaScript

You can use a .js file in the ECMAScript compliant JavaScript language to define the service logic of an HML page. With dynamic typing, JavaScript can make your application more expressive with a flexible design. The following describes the JavaScript compilation and running.

Syntax

The ECMAScript 6.0 syntax is supported. Lite wearables only support the following ECMAScript 6.0 syntax:

1. let/const

2. arrow functions

3. class

4. default value

5. destructuring assignment

6. destructuring binding pattern

7. enhanced object initializer

8. for-of

9. rest parameter

10. template strings

• Module declaration Import functionality modules.

  import router from '@system.router';
  

• Code reference Import JavaScript code.

  import utils from '../../common/utils.js';
  

Objects

• Page objects

Obtaining a DOM Element

Use $refs to obtain a DOM element.

<!-- index.hml -->
<div class="container">
  <image-animator class="image-player" ref="animator" images="{{images}}" duration="1s" onclick="handleClick"></image-animator>
</div>

// index.js
export default {
  data: {
    images: [
      { src: '/common/frame1.png' },
      { src: '/common/frame2.png' },
      { src: '/common/frame3.png' },
    ],
  },
  handleClick() {
    const animator = this.$refs.animator; // Obtain the DOM element whose $refs attribute is animator.
    const state = animator.getState();
    if (state === 'paused') {
      animator.resume();
    } else if (state === 'stopped') {
      animator.start();
    } else {
      animator.pause();
    }
  },
};

Lifecycle APIs

• Page lifecycle APIs

The lifecycle APIs of page A are called in the following sequence:

• Open page A: onInit() -> onReady() -> onShow()

• Open page B on page A: onHide() -> onDestroy()

• Go back to page A from page B: onInit() -> onReady() -> onShow()

• Exit page A: onHide() -> onDestroy()

• Hide page A: onHide()

• Show background page A on the foreground: onShow()

• Application lifecycle APIs