Improvements of Vue3 over Vue2: more efficient list rendering

Improvements of Vue3 over Vue2: More efficient list rendering

As a popular JavaScript front-end framework, Vue provides a simple and easy-to-use data-driven view, as well as efficient list rendering functions. However, in Vue2, performance issues may arise when dealing with lists of large amounts of data. To solve this problem, Vue3 has introduced some improvements to make list rendering more efficient and improve user experience. This article will explore Vue3's improvements in list rendering compared to Vue2 and provide relevant code examples.

In Vue2, when we use the v-for directive to render a large-scale data list, each list item will be bound to a listener, which will cause an increase in performance overhead. In Vue3, Vue3 implements more efficient list rendering by introducing a new API - Collection.

First, we need to import Vue3 related dependencies in the code:

import { createApp, h } from 'vue';

Next, we can use the Collection feature to create a simple list component:

const List = {
  render() {
    return h('ul', this.items.map(item => h('li', item)));
  },
  data() {
    return {
      items: ['item1', 'item2', 'item3', ... 'item10000']
    };
  }
};

createApp(List).mount('#app');

In the above code, we create a ul element through the h function, and use the map function to render the data in the items array in each li element. The items array in the above code contains 10,000 list items, simulating a large-scale data list.

In Vue2, each list item will be bound to a listener, which will bring performance overhead. In Vue3, Vue3 will wrap the entire list item in a collection (Collection) and render it using virtual DOM features. This means that no matter what the size of the list is, Vue3 only needs to bind one listener, greatly reducing memory usage and rendering time.

In addition, Vue3 also introduces a new responsive system-Proxy. Proxy provides more efficient list rendering compared to Object.defineProperty used in Vue2. By using Proxy, Vue3 can track data changes more efficiently and render accordingly.

The following is an example of list rendering using Proxy:

const List = {
  render() {
    return h('ul', this.items.map(item => h('li', item)));
  },
  setup() {
    const items = new Proxy([], {
      set(target, prop, value) {
        target[prop] = value;
        // 触发渲染
      }
    });

    // 模拟向 items 数组中添加数据
    for (let i=0; i<10000; i++) {
      items.push(`item${i}`);
    }

    return { items };
  }
};

createApp(List).mount('#app');

In the above code, we use a Proxy object to track changes in the items array. When data is added to the items array, the Proxy triggers the set method and updates the view. Compared with the Object.defineProperty method in Vue2, using Proxy can better monitor and update data, improving the performance of list rendering.

To sum up, Vue3 has made some improvements compared to Vue2 to make list rendering more efficient. Through the introduction of Collection and Proxy, Vue3 achieves more efficient and faster list rendering, improving user experience.

Note: The above code example is based on the Composition API of Vue3. If you are using Vue2 or other versions of Vue, please adjust the code accordingly.

Reference:

• Vue Composition API: https://composition-api.vuejs.org/
• Evan You. (2019). Vue 3's Reactivity System Explained. https://www.vuemastery.com/blog/vue-3s-reactivity-system-explained/

The above is the detailed content of Improvements of Vue3 over Vue2: more efficient list rendering. For more information, please follow other related articles on the PHP Chinese website!