Essential skills for Vue development: clever use of v-if, v-show, v-else, v-else-if to achieve conditional rendering

Essential skills for Vue development: skillfully use v-if, v-show, v-else, v-else-if to achieve conditional rendering

In Vue development , conditional rendering is a very common operation. Vue provides a series of instructions to implement conditional rendering, including v-if, v-show, v-else, v-else-if, etc. This article will use specific code examples to introduce how to skillfully use these instructions to implement conditional rendering to improve development efficiency and code readability.

1. v-if instruction

The v-if instruction is used to render or destroy elements based on specified conditions. If the condition evaluates to true, the element will be rendered; if the condition evaluates to false, the element will be destroyed. The following is a simple example:

<div v-if="show">
  <p>这是一个条件渲染的示例</p>
</div>

In the Vue instance, by modifying the value of show, you can control the rendering and destruction of the element:

data() {
  return {
    show: true
  }
}

2. v-show instruction

Similar to v-if, v-show is also used to show or hide elements based on specified conditions. The difference is that v-show works by modifying the CSS display property of the element instead of directly rendering or destroying the element. The sample code is as follows:

<div v-show="show">
  <p>这是一个条件渲染的示例</p>
</div>

Unlike v-if, v-show does not destroy the element, but only controls whether the element is displayed through CSS. Therefore, v-show works better on elements that need to be frequently switched between showing and hiding.

3. v-else instruction

The v-else instruction is used to add an "else" block after the v-if or v-else-if instruction. It must immediately follow an element with v-if or v-else-if and no expression. The sample code is as follows:

<div>
  <p v-if="show">显示内容</p>
  <p v-else>隐藏内容</p>
</div>

In the above code, if the value of show is true, the "display content" is displayed; if the value of show is false, the "hidden content" is displayed.

4. v-else-if instruction

The v-else-if instruction is used to add an "else if" block after the v-if or v-else-if instruction. It must immediately follow an element with v-if or v-else-if, and an expression needs to be provided. The sample code is as follows:

<div>
  <p v-if="type === 'A'">类型A</p>
  <p v-else-if="type === 'B'">类型B</p>
  <p v-else-if="type === 'C'">类型C</p>
  <p v-else>其他类型</p>
</div>

In the above code, different types are displayed based on the value of type.

The above are examples of conditional rendering through v-if, v-show, v-else, v-else-if instructions. In actual development, selecting appropriate instructions based on needs can more flexibly handle conditional rendering requirements.

Summary:

1. The v-if directive is used to render or destroy elements based on conditions.
2. The v-show directive is used to show or hide elements based on conditions.
3. The v-else directive is used to add an "else" block.
4. The v-else-if directive is used to add an "else if" block.
5. Choose appropriate instructions according to needs to improve development efficiency and code readability.

I hope this article can help you understand how to skillfully use v-if, v-show, v-else, and v-else-if instructions to achieve conditional rendering. Different instructions have different advantages in different scenarios. Through flexible use, development efficiency and code quality can be improved.

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