nextTick function in Vue3: processing operations after DOM update

Vue3 is a very popular front-end framework recently. Its biggest feature is virtual DOM technology, that is, Vue will convert the real DOM tree into a virtual DOM tree, and then convert it after operating on the virtual DOM tree. For the real DOM tree. This technology allows us to operate DOM more efficiently, and can also achieve very good performance when the number of DOM is large. However, due to the particularity of virtual DOM technology, when we operate DOM, sometimes we cannot obtain the latest DOM information immediately. In this case, we need to use the nextTick function in Vue3.

Usage of nextTick function in Vue3

The nextTick function in Vue3 is a function provided by Vue to operate DOM asynchronously. Its specific usage is to call Vue.nextTick() in a function , this function will be executed after the current DOM update is completed. The latest DOM data can be obtained from the incoming callback function to perform corresponding operations. For example:

// 引入Vue依赖
import { createApp, nextTick } from 'vue'

// 创建Vue实例
const app = createApp({
  // ...
})

// 定义一个data属性
data () {
  return {
    message: 'Hello Vue!'
  }
}

// 在逻辑中改变message属性
this.message = 'Hello World!'

// 执行nextTick函数
nextTick(() => {
  // 获取最新的DOM信息并进行相应的操作
  console.log(this.$el.innerText) //输出: Hello World!
})

The principle of nextTick

In Vue3, although virtual DOM technology can make DOM operations more efficient, due to the particularity of this technology, we sometimes cannot immediately To obtain the latest DOM data, you need to use the nextTick function. The principle of the nextTick function is actually relatively simple. When we change a DOM attribute in the logic, Vue will update the DOM value at the next "tick". This update time happens to be when the nextTick function is executed. After the nextTick function is executed, we can obtain the latest DOM data and perform corresponding operations.

nextTick use case

nextTick function is widely used, especially when using virtual DOM technology in Vue3, it is indispensable. In the following case, we can see that in the compsed API, we call the nextTick function to ensure that the DOM is updated before performing the corresponding operation:

import { ref, onMounted, nextTick } from 'vue'

export default {
  setup() {
    // 定义一个ref对象
    const message = ref('Hello Vue!')

    // 创建一个onMounted钩子，当页面加载后执行
    onMounted(() => {
      // 获取最新的DOM信息并进行相应的操作
      nextTick(() => {
        console.log(this.$el.innerText) //输出: Hello Vue!
      })
    })

    // 返回引用
    return {
      message
    }
  }
}

Summary

This article mainly introduces The nextTick function in Vue3 points out that when using virtual DOM technology, there will be a delay in obtaining the latest DOM information, explains the usage and principle of the nextTick function, and illustrates the application scenarios of the nextTick function through examples. In short, the nextTick function in Vue3 is a very important function. It allows us to better handle DOM updated operations and improves the overall development efficiency.

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