The ultimate secret to Vue conditional rendering: Use v-if, v-show, v-else, v-else-if to build an efficient dynamic interface

Vue is a popular JavaScript framework that provides many useful instructions to help developers build dynamic interfaces. Among them, conditional rendering is an important feature in the Vue framework. By using instructions such as v-if, v-show, v-else, and v-else-if, we can dynamically show or hide elements based on conditions to build efficient dynamic interfaces. This article explains how to use these directives to implement conditional rendering and provides specific code examples.

1. v-if directive
   v-if is one of the most commonly used conditional rendering directives in Vue. It decides whether to render the DOM element based on whether the condition is true or false. If the condition is true, the element is rendered; if the condition is false, the element is not rendered.

Code example:

<template>
  <div>
    <p v-if="isShow">条件为真，渲染该元素</p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      isShow: true
    };
  }
};
</script>

In the above example, when isShow is true, the p element containing the text "Condition is true, render this element" is rendered. When isShow is false, the p element will not be rendered.

2. v-show instruction
   The v-show instruction is similar to the v-if instruction. It also determines whether the element is displayed based on the true or false condition. The difference is that v-show controls the display and hiding of elements through the display attribute of CSS. If the condition is true, the element is shown; if the condition is false, the element is hidden.

Code example:

<template>
  <div>
    <p v-show="isShow">条件为真，显示该元素</p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      isShow: true
    };
  }
};
</script>

In the above example, when isShow is true, the p element will be displayed; when isShow is false, the p element will be hidden.

3. v-else and v-else-if directives
   The v-else and v-else-if directives are used to set "else" and "else if" logic in conditional rendering. They must immediately follow an element with a v-if or v-else-if directive and cannot be used alone.

Code example:

<template>
  <div>
    <p v-if="score >= 60">恭喜，你及格了！</p>
    <p v-else-if="score >= 40">很遗憾，你需要补考。</p>
    <p v-else>抱歉，你不及格。</p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      score: 75
    };
  }
};
</script>

In the above example, depending on the value of score, different text will be displayed.

Summary:
By using instructions such as v-if, v-show, v-else and v-else-if, we can flexibly build dynamic interfaces based on conditions. In actual development, selecting appropriate conditional rendering instructions according to specific needs can improve the performance and user experience of the interface. I hope the code examples provided in this article can help readers better understand and apply these Vue conditional rendering instructions.

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