Improvements of Vue3 compared to Vue2: more efficient virtual DOM

Improvements of Vue3 over Vue2: More efficient virtual DOM

With the continuous development of front-end technology, Vue, as a popular JavaScript framework, is also constantly evolving. As an upgraded version of Vue2, Vue3 brings some important improvements, the most significant of which is a more efficient virtual DOM.

Virtual DOM (Virtual DOM) is one of the key mechanisms used to improve performance in Vue. It allows the framework to maintain a virtual DOM tree internally, and then minimize the number of DOM operations by comparing the changes in the virtual DOM tree with the actual DOM tree.

In Vue2, the virtual DOM update mechanism is implemented by comparing the differences between the old and new virtual DOM trees. However, this algorithm can cause performance issues when dealing with large applications because it requires a layer-by-layer depth-first comparison of the entire virtual DOM tree.

To solve this problem, Vue3 introduces a new virtual DOM algorithm called Proxy-based virtual DOM tracking. This new algorithm is based on the Proxy feature of ES6. By tracking responsive data access, it only performs dependency tracking and updates on the data that is actually accessed. This method avoids the performance overhead of traversing the entire virtual DOM tree, making virtual DOM updates more efficient.

The following is a simple example showing the usage of Proxy-based virtual DOM tracking in Vue3:

<!-- index.html -->
<div id="app"></div>

<!-- main.js -->
import { createApp, reactive } from 'vue';

const app = createApp({
  setup() {
    // 使用reactive创建响应式对象
    const state = reactive({
      count: 0
    });

    // 返回state对象
    return {
      state
    };
  },
  render() {
    // 响应式数据绑定到模板上
    return (
      <div>
        <p>Count: {this.state.count}</p>
        <button onClick={() => this.state.count++}>Increment</button>
      </div>
    );
  }
});

// 将Vue应用挂载到DOM上
app.mount('#app');

Through the above example, we can see that in Vue3, we use reactive function to create a responsive state object. We can then reference state.count directly in the template and when the button is clicked, state.count will automatically update and re-render.

It should be noted that the state object here is a proxy object. It only tracks the data actually accessed by the template and does not traverse the entire layer-by-layer depth-first comparison virtual DOM tree. . This proxy-based tracking mechanism makes Vue3 more efficient when handling large applications.

To sum up, Vue3 brings an important improvement compared to Vue2, that is, a more efficient virtual DOM. Through the Proxy-based virtual DOM tracking mechanism, Vue3 can provide better performance when processing large applications. As front-end developers, we can use the new features of Vue3 to optimize our applications and improve user experience.

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