How to use js to achieve the effect of hiding the view in the uniapp project

UniApp is a cross-platform development tool based on the Vue.js framework. It has a rich component library and API and can quickly develop high-quality cross-platform applications. In actual development, we often need to control the display and hiding of certain view components on the page. This article will introduce how to use JavaScript to achieve the effect of hiding views in UniApp.

1. Use the v-if directive to achieve dynamic rendering of views

In Vue.js, use the v-if directive to conditionally render view components. The same applies in UniApp. We can control the display and hiding of view components based on the true or false value of a certain variable.

For example, if we need to control the display and hiding of a button component, we can define a variable isShowButton in the data model:

<template>
  <!-- 视图组件 -->
  <button>按钮</button>
</template>
 
<script>
export default {
  data() {
    return {
      isShowButton: true   // 控制按钮组件的显示与隐藏
    }
  }
}
</script>

When the value of the isShowButton variable is true, the button component will be rendered. out; when the variable value is false, the button component will be hidden. We can dynamically change the value of the isShowButton variable in the program to achieve dynamic rendering of the view component.

2. Use the v-show instruction to achieve static rendering of the view

If the view component we need to control is rendered more times on the page, frequent dynamic rendering will affect Program performance, you can use the v-show command to control the display and hiding of components.

The principle of v-show is to display and hide view components through the display attribute of CSS. When the value of v-show is true, the component's display attribute is set to block, and the component will be displayed; when the value of v-show is false, the component's display attribute is set to none, and the component will be hidden.

For example, if we need to control the display and hiding of a picture component, we can use the v-show instruction:

<template>
  <!-- 视图组件 -->
  <img  src="/static/imghwm/default1.png" data-src="imageUrl" class="lazy" alt="How to use js to achieve the effect of hiding the view in the uniapp project" >
</template>
 
<script>
export default {
  data() {
    return {
      imageUrl: &#39;https://some.image.url&#39;,
      isShowImage: false   // 控制图片组件的显示与隐藏
    }
  }
}
</script>

In this example, when the value of the isShowImage variable is true, the picture component will be displayed; when the variable value is false, the picture component will be hidden. By changing the value of the isShowImage variable in the data model, we can achieve static rendering and hiding of the picture component.

3. Use JavaScript to dynamically control the style of the view component

If we need to more finely control the display and hiding of the view component (for example: need to change the transparency, position, etc. of the component) Properties), you can use JavaScript to dynamically control the style of the view component.

In UniApp, the view components of the current page can be operated through the uni-app global variable. We can obtain the specified component through the $refs attribute of uni-app and change its style.

For example, we need to dynamically control the transparency of a div component, which can be achieved using the following code:

<template>
  <!-- 视图组件 -->
  <div>Hello, UniApp!</div>
</template>
 
<script>
export default {
  mounted() {
    // 获取div组件
    const myDiv = this.$refs.myDiv;
 
    // 设置div组件透明度为0.5
    myDiv.style.opacity = 0.5;
  }
}
</script>

In this example, we obtain the div component in the mounted hook function of the component, and Change the transparency by setting its style. We can use JavaScript to dynamically control the styles of view components according to the needs of the program, achieving more precise control of components on the page.

Summary

Through the above three methods, we can use JavaScript in UniApp to control the display and hiding of view components on the page, realizing the need for dynamic changes in the page. In actual development, we can flexibly use these techniques to quickly develop high-quality cross-platform applications.

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