The difference between Vue3 and Vue2: clearer code structure

The difference between Vue3 and Vue2: Clearer code structure

Vue.js is a popular JavaScript framework for building user interfaces. In the development history of Vue.js, Vue2 is an extremely successful version. However, Vue3 brings some exciting changes, providing a clearer code structure and more powerful performance. This article will focus on some of the main differences between Vue3 and Vue2, and illustrate them with code examples.

1. Composition API (Combined API)
   Vue3 introduces a new Composition API, which provides a more flexible way of organizing code. Compared with Vue2's Options API, the Composition API makes the code more modular and maintainable.

The following is an example of a Vue2 component:

<template>
  <div>
    <h1>{{ message }}</h1>
    <button @click="increment">Increment</button>
  </div>
</template>

<script>
export default {
  data() {
    return {
      message: 'Hello Vue!',
      count: 0
    }
  },
  methods: {
    increment() {
      this.count++
    }
  }
}
</script>

In Vue3, you can use the Composition API to rewrite the above component:

<template>
  <div>
    <h1>{{ message }}</h1>
    <button @click="increment">Increment</button>
  </div>
</template>

<script>
import { reactive, computed } from 'vue'

export default {
  setup() {
    const state = reactive({
      message: 'Hello Vue!',
      count: 0
    })

    const increment = () => {
      state.count++
    }

    return {
      ...toRefs(state),
      increment
    }
  }
}
</script>

In the Composition API of Vue3 , we use the reactive function to create responsive data, and the computed function to create computed properties. Convert responsive data into ordinary references by using the toRefs function for access in templates.

2. Better performance
   Vue3 also has many improvements in performance, the most eye-catching of which is the improved implementation of virtual DOM (Virtual DOM).

In Vue2, changes in responsive data will cause the entire component to be re-rendered, which may cause performance issues in some large applications. Vue3 uses a proxy-based observer mechanism to more accurately track changes in responsive data and only re-render the affected parts, thereby improving performance.

3. TypeScript support
   Vue3’s support for TypeScript has also been improved a lot. Vue3's code base has been written entirely in TypeScript and provides better type inference and type checking.

In Vue3, you can use TypeScript decorators to define component types, annotations and dependency injection. This makes it easier for developers to perform static type checking and reduce potential runtime errors.

To sum up, Vue3 has brought some exciting changes compared to Vue2. By introducing the Composition API, Vue3 provides a more flexible and modular way of organizing code. At the same time, Vue3 has also been greatly improved in terms of performance. By improving the implementation of virtual DOM, it can more accurately track changes in responsive data and improve performance. In addition, Vue3's support for TypeScript is also more complete, making it easier for developers to perform static type checking.

I hope this article can help readers better understand the differences between Vue3 and Vue2, and better use Vue.js in daily development.

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