The difference between Vue3 and Vue2: a new responsive system

The difference between Vue3 and Vue2: a new responsive system

Vue.js is a popular JavaScript framework for building user interfaces. It simplifies data-driven development and provides a powerful, responsive system. Vue3 is the latest version of Vue.js. Compared with Vue2, it introduces a new responsive system, which brings many advantages to developers. In this article, we’ll take a deep dive into the differences between Vue3 vs. Vue2 and illustrate the benefits of these differences with some example code.

1. Proxy Agent

Vue2 uses Object.defineProperty to implement its responsive system. While this approach works, it has some limitations. Vue3 uses Proxy instead to implement a responsive system, which brings more flexibility and functionality to developers.

Sample code 1: Responsive definition of Vue2

let data = { count: 0 };
Object.defineProperty(data, 'count', {
  get() {
    console.log('get count');
    return count;
  },
  set(newVal) {
    console.log('set count');
    count = newVal;
  }
});

Sample code 2: Responsive definition of Vue3

let data = { count: 0 };
let reactiveData = new Proxy(data, {
  get(target, key) {
    console.log('get ' + key);
    return Reflect.get(target, key);
  },
  set(target, key, value) {
    console.log('set ' + key);
    return Reflect.set(target, key, value);
  }
});

As can be seen from the above sample code, Vue3’s Proxy agent By implementing get and set monitoring, we can more easily track data changes.

2. Ref reference type

In Vue3, the Ref reference type is added to solve some problems in the responsive system in Vue2. Ref provides better reactive support by resolving the differences between value types and reference types.

Sample code 3: Ref reference type of Vue3

import { ref } from 'vue';

let count = ref(0);

console.log(count.value);  // 输出0

count.value = 1;  // 修改值

console.log(count.value);  // 输出1

As can be seen from the sample code, the Ref reference type in Vue3 can access the value through the value attribute, and can also modify the value directly. This makes reading and updating data easier and more intuitive.

3. Setup function

In Vue3, a new hook function-Setup function is introduced, which replaces the data, computed, methods and other options in Vue2. The Setup function provides a clearer and more flexible component API, allowing developers to better organize and manage code.

Sample code 4: Setup function of Vue3

import { ref } from 'vue';

export default {
  setup() {
    let count = ref(0);

    function increment() {
      count.value++;
    }

    return {
      count,
      increment
    };
  }
}

As can be seen from the above code example, using the Setup function to define components allows developers to better encapsulate and manage data and methods. This helps improve code readability and maintainability.

Summary:
In this article, we compare the differences between Vue3 and Vue2, focusing on the new responsive system. Vue3 uses Proxy to implement responsiveness, providing greater flexibility and functionality. At the same time, the Ref reference type and Setup function are introduced, allowing developers to better organize and manage code. These improvements provide developers with a better development experience and performance optimization. Of course, individuals need to choose between Vue3 or Vue2 based on the actual needs of the project, but it is certain that the changes brought by Vue3 will further improve development efficiency and code quality.

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