The difference between Vue3 and Vue2: rewritten compiler

The difference between Vue3 and Vue2: rewritten compiler

Vue is a popular front-end framework. Its large community and strong ecosystem make Vue the first choice for many developers. In the release of Vue3, one of the biggest changes was the rewriting of the compiler. This article will introduce in detail the changes brought about by the rewritten compiler in Vue3, and use code examples to deepen understanding.

1. Rewritten compiler

1. Vue2 compiler

In Vue2, the main function of the compiler is to compile the Vue template into The executable rendering function will parse and process the instructions, components, events, etc. in the template during the compilation process. Vue2 uses a compiler based on string operations to convert template strings into rendering functions. This method will have a performance bottleneck when processing large and complex templates.

2. Vue3 compiler

In Vue3, the compiler has been completely rewritten, adopting a more efficient compilation method, and using AST (Abstract Syntax) tree) compiler. AST is a data structure that describes the structure of the code. Compilation performance is improved by parsing the template and generating AST, and then traversing the AST to optimize and generate rendering functions.

2. Advantages of the Vue3 compiler

1. Higher performance

By using AST to optimize and generate rendering functions, the Vue3 compiler is Performance has been significantly improved. Compared with Vue2's string manipulation method, Vue3's compiler can more accurately analyze the structure and dependencies of templates and generate more efficient code. This can significantly improve the application's rendering performance in the case of large and complex templates.

2. Smaller package size

The Vue3 compiler has been optimized to generate smaller code than Vue2. This means that when using Vue3 to build an application, the packaged file size can be reduced and the application loading speed can be improved. This is especially important for mobile application development.

3. Code Example

In order to better demonstrate the advantages of the Vue3 compiler, let’s compare it with a simple example. Suppose there is a Vue component, the template contains a loop list, and there is some complex logic in the loop body.

Vue2 is written as follows:

<template>
  <div>
    <ul>
      <li v-for="item in list" :key="item.id">
        <span>{{ item.title }}</span>
        <button @click="handleButtonClick(item.id)">点击</button>
      </li>
    </ul>
  </div>
</template>

<script>
export default {
  data() {
    return {
      list: [...]
    }
  },
  methods: {
    handleButtonClick(id) {
      // 复杂的逻辑...
    }
  }
}
</script>

Vue3 is written as follows:

<template>
  <div>
    <ul>
      <li v-for="item in list" :key="item.id">
        <span>{{ item.title }}</span>
        <button @click="() => handleButtonClick(item.id)">点击</button>
      </li>
    </ul>
  </div>
</template>

<script>
import { ref } from 'vue';

export default {
  setup() {
    const list = ref([...]);
    const handleButtonClick = (id) => {
      // 复杂的逻辑...
    };

    return {
      list,
      handleButtonClick
    };
  }
}
</script>

In the above code example, the template structure of Vue2 and Vue3 is the same, but in Vue3 You can use the more concise setup function to write the logical part of the component. setupThe function returns an object, which contains the component's data and methods. At the same time, the ref function was introduced in Vue3 to create responsive data, replacing the data attribute in Vue2. These improvements make the code clearer and more concise, improving development efficiency.

Summary

Vue3's rewritten compiler is one of the biggest improvements of Vue3. It improves the performance of compilation and smaller package size by using AST for optimization and generation of rendering functions. . In actual application development, especially in the case of large and complex templates, the performance advantages brought by the Vue3 compiler are more obvious. At the same time, use the setup function to write the logical part of the component, making the code clearer and more concise. Therefore, we have reason to believe that the Vue3 compiler will play an important role in the development of Vue.

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