Deeply understand the Composition API in Vue 3 to improve code reusability

In-depth understanding of the Composition API in Vue 3 to improve code reusability

Introduction:
Vue 3 is a large, powerful JavaScript framework that helps development People build interactive user interfaces. As one of the important features of Vue 3, the Composition API provides a more flexible, composable and reusable way to develop components. This article will provide an in-depth understanding of the Composition API in Vue 3 and show how it improves code reusability through code examples.

1. Introduction to Composition API
Composition API is a new feature in Vue 3. It allows us to use functional APIs in components to organize and manage logic code. Compared to the option-based API in Vue 2, the Composition API is more readable and maintainable when dealing with large and complex components.

2. Advantages of Composition API

1. More composable: Composition API provides a way to split logical code into composable functions. We can create independent functions and then call them on demand, achieving more flexible code organization and reuse.
2. More intuitive logical relationships: Composition API separates the logic code from the declarative template of the component, reducing the complexity of the component code. We can organize related logic together through functions and interact through function calls.
3. Better type inference: Composition API takes advantage of TypeScript's type inference to make the static type checking of the code more accurate. Developers can get better development experience and error prompts when writing code.

3. Code Example
Below we use a specific example to demonstrate how the Composition API improves code reusability.

<template>
  <div>
    <h1 id="用户列表">用户列表</h1>
    <ul>
      <li v-for="user in users" :key="user.id">{{ user.name }}</li>
    </ul>
    <button @click="fetchUsers">加载用户</button>
  </div>
</template>

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

export default {
  name: 'UserList',
  setup() {
    const users = ref([]);

    const fetchUsers = async () => {
      const response = await fetch('https://api.example.com/users');
      const data = await response.json();
      users.value = data;
    };

    onMounted(() => {
      fetchUsers();
    });

    return {
      users,
      fetchUsers,
    };
  },
};
</script>

The above code example defines a component named UserList. We create a reactive data called users through the ref function, which saves the user list in an internal array. fetchUsersThe function is used to obtain the user list through network requests and assign the result to users.

Through the onMounted hook, we automatically call the fetchUsers function to load the user list when the component is mounted. In this way, we separate the logic of obtaining the user list from the component life cycle, making the logic code clearer and reusable.

At the same time, we return both users and fetchUsers to the template part of the component for use. In the template, we traverse the users array through the v-for directive and display the name of each user.

In the above example, we can see how the Composition API abstracts the logic code into independent functions and implements logic execution through function calls. This approach makes the component's logic easier to read and maintain, and makes it easier to reuse the logic.

Conclusion:
This article introduces the Composition API in Vue 3 and shows how to use the Composition API to improve code reusability through sample code. The Composition API makes logical code more composable and readable, helping developers better organize and manage the logical parts of components. In actual development, we should give full play to the advantages of Composition API and improve the reusability and maintainability of code.

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