Advanced application skills of Vue conditional rendering: skillfully use v-if, v-show, v-else, v-else-if to create complex interfaces

Advanced application skills of Vue conditional rendering: skillfully use v-if, v-show, v-else, v-else-if to create complex interfaces

Introduction:
Vue is a popular JavaScript framework that helps developers build responsive user interfaces. Vue provides powerful conditional rendering capabilities, including instructions such as v-if, v-show, v-else, and v-else-if. These instructions can dynamically render or display elements based on conditions, thereby realizing the display and interaction of complex interfaces.

This article will introduce how to skillfully use v-if, v-show, v-else and v-else-if instructions to implement complex interfaces, and provide specific code examples.

1. v-if: The
   v-if directive is used to render an element or component that will only be rendered if the condition is true. For example, we can show different components based on the user's logged-in status:

<template>
  <div>
    <div v-if="isLoggedIn">
      用户已登录
    </div>
    <div v-else>
      用户未登录
    </div>
  </div>
</template>

<script>
export default {
  data() {
    return {
      isLoggedIn: false
    };
  }
};
</script>

2. v-show: The
   v-show directive is also used to show or hide elements based on conditions, but It does this by modifying the element's CSS properties, rather than actually rendering the element into the DOM. This means that the v-show command performs better when switching between showing and hiding. In the following example, we can display different buttons based on the user's permissions:

<template>
  <div>
    <button v-show="isAdmin">删除</button>
    <button v-show="!isAdmin">只读</button>
  </div>
</template>

<script>
export default {
  data() {
    return {
      isAdmin: false
    };
  }
};
</script>

3. v-else and v-else-if: The
   v-else directive is used to Switch between adjacent elements of the v-if instruction, which means "otherwise". The v-else directive must immediately follow the v-if directive, and no other elements or directives can be inserted into it. For example, we can display different ads based on the user's age group:

<template>
  <div>
    <div v-if="age < 18">
      <img  src="kids-ad.jpg" alt="Advanced application skills of Vue conditional rendering: skillfully use v-if, v-show, v-else, v-else-if to create complex interfaces" >
    </div>
    <div v-else-if="age < 40">
      <img  src="adults-ad.jpg" alt="Advanced application skills of Vue conditional rendering: skillfully use v-if, v-show, v-else, v-else-if to create complex interfaces" >
    </div>
    <div v-else>
      <img  src="elderly-ad.jpg" alt="Advanced application skills of Vue conditional rendering: skillfully use v-if, v-show, v-else, v-else-if to create complex interfaces" >
    </div>
  </div>
</template>

<script>
export default {
  data() {
    return {
      age: 25
    };
  }
};
</script>

It should be noted that the v-else-if directive must be followed immediately by the v-if or v-else-if directive After that, no other elements or directives can be inserted into it.

Conclusion:
Vue’s conditional rendering function provides a variety of instructions, such as v-if, v-show, v-else and v-else-if, which can dynamically render according to different conditions. and display elements. This article details the use of these directives and provides specific code examples. By cleverly using these instructions, developers can easily display and interact with complex interfaces.

In short, Vue’s conditional rendering function is one of the important tools for developing complex interfaces and is worthy of in-depth study and mastery by developers.

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