How to use v-if and v-else combined to achieve dual conditional rendering in Vue

Vue is an excellent front-end framework. It is easy to learn, efficient, flexible, and scalable, so it is widely loved by front-end developers. In Vue, v-if and v-else are two commonly used instructions. They can help us render different content under different conditions. This article will introduce how to use v-if and v-else to achieve dual conditional rendering in Vue.

1. v-if and v-else

In Vue, v-if is an instruction for conditional judgment. It can decide whether to render a certain object based on given conditions. element. For example:

<div v-if="isShow">这是一个显示区域</div>

When isShow is true, this div will be rendered; when isShow is false, this div will be deleted from the DOM.

v-else is a supplementary instruction to v-if, which is used to render another element when the condition of v-if is false. For example:

<div v-if="isShow">这是一个显示区域</div>
<div v-else="">这是一个隐藏区域</div>

When isShow is true, the first div will be rendered, and the second div will be hidden; when isShow is false, the first div will be hidden, and the second div will be hidden. A div will be rendered.

2. Use v-if and v-else to implement dual conditional rendering

Sometimes, we need to render different content based on two conditions, then we can use v-if Combined with v-else, dual conditional rendering is achieved. For example: We need to render different content based on the user's gender and age. If the user is male and older than 30 years old, we render "You have entered middle age", otherwise we render "You are still young".

First, we need to define two variables, gender and age, in the Vue instance. These two variables represent the user's gender and age respectively.

data() {
  return {
    gender: 'male',
    age: 25
  }
}

Then, you can write this in the template:

<div v-if="gender === 'male' && age > 30">您已经步入中年</div>
<div v-else>您还年轻</div>

If gender is male and age is greater than 30, the first div will be rendered; otherwise the second div will be rendered come out.

3. Summary

Using v-if combined with v-else can easily achieve dual conditional rendering. In actual development, we can reasonably use Vue instructions according to needs to achieve different needs. At the same time, we also need to pay attention to the usage of instructions and performance issues, reasonably optimize the code, and improve page performance and user experience.

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