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 ES6 syntax is supported.

• Module declaration

  Import functionality modules.

  import router from '@ohos.router';
  

• Code reference

  Import JavaScript code.

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

Objects

• Application objects

Example

// app.js
export default {
  onCreate() {
    console.info('Application onCreate');
  },
  onDestroy() {
    console.info('Application onDestroy');
  },
  globalData: {
    appData: 'appData',
    appVersion: '2.0',
  },
  globalMethod() {
    console.info('This is a global method!');
    this.globalData.appVersion = '3.0';
  }
};

// index.js
export default {
  data: {
    appData: 'localData',
    appVersion:'1.0',
  },
  onInit() {
    this.appData = this.$app.$def.globalData.appData;
    this.appVersion = this.$app.$def.globalData.appVersion;
  },
  invokeGlobalMethod() {
    this.$app.$def.globalMethod();
  },
  getAppVersion() {
    this.appVersion = this.$app.$def.globalData.appVersion;
  }
}

• Page objects

Methods

• Data methods

Example

// index.js
export default {
  data: {
    keyMap: {
      OS: 'OpenHarmony',
      Version: '2.0',
    },
  },
  getAppVersion() {
    this.$set('keyMap.Version', '3.0');
    console.info("keyMap.Version = " + this.keyMap.Version); // keyMap.Version = 3.0

    this.$delete('keyMap');
    console.info("keyMap.Version = " + this.keyMap); // log print: keyMap.Version = undefined
  }
}

• Public methods

• Event methods

• Page methods

Table 1 ScrollPageParam⁶⁺

Example

this.$rootElement().scrollTo({position: 0})
this.$rootElement().scrollTo({id: 'id', duration: 200, timingFunction: 'ease-in', complete: ()=>void})

Obtaining a DOM Element

1. 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();
       }
     },
   };
   

2. Call $element to obtain a DOM element.

   <!-- index.hml -->
   <div class="container" style="width:500px;height: 700px; margin: 100px;">
     <image-animator class="image-player" id="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.$element('animator'); // Obtain the DOM element whose ID is animator.
       const state = animator.getState();
       if (state === 'paused') {
         animator.resume();
       } else if (state === 'stopped') {
         animator.start();
       } else {
         animator.pause();
       }
     },
   };
   

Obtaining the ViewModel

The following shows files of the root page:

<!-- root.hml -->
<element name='parentComp' src='../../common/component/parent/parent.hml'></element>
<div class="container">
  <div class="container">
    <text>{{text}}</text>
    <parentComp></parentComp>
  </div>
</div>

// root.js
export default {
  data: {
    text: 'I am a root!',
  },
}

Customize the parent component.

<!-- parent.hml -->
<element name='childComp' src='../child/child.hml'></element>
<div class="item" onclick="textClicked">
  <text class="text-style" onclick="parentClicked">parent component click</text>
  <text class="text-style" if="{{showValue}}">hello parent component!</text>
  <childComp id = "selfDefineChild"></childComp>
</div>

// parent.js
export default {
  data: {
    showValue: false,
    text: 'I am parent component!',
  },
  parentClicked () {
    this.showValue = !this.showValue;
    console.info('parent component get parent text');
    console.info(`${this.$parent().text}`);
    console.info("The parent component gets the child function.");
    console.info(`${this.$child('selfDefineChild').childClicked()}`);
  },
}

Customize the child component.

<!-- child.hml -->
<div class="item" onclick="textClicked">
  <text class="text-style" onclick="childClicked">Child component clicked</text>
  <text class="text-style" if="{{isShow}}">Hello child component</text>
</div>

// child.js
export default {
  data: {
    isShow: false,
    text: 'I am the child component!',
  },
  childClicked () {
    this.isShow = !this.isShow;
    console.info('child component get parent text');
    console.info('${this.$parent().text}');
    console.info('child component get root text');
    console.info('${this.$root().text}');
  },
}