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 '@ohos.router';

  • Code reference

    Import JavaScript code.

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

Objects

  • Page objects
Attribute Type Description
data Object/Function Data model of the page. If the attribute is of the function type, the return value must be of the object type. The name cannot start with a dollar sign ($) or underscore (_). Do not use reserved words (for, if, show, and tid).
$refs Object DOM elements or child component instances that have registered the ref attribute. For an example, see Obtaining a DOM Element.

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();
    }
  },
};