This article will give you an in-depth understanding of the use of Composition API in Vue3

Vue 3 brings many exciting new features, one of the most notable is the Composition API. The Composition API is a powerful feature in Vue 3 that improves code organization and reuse, making building components more flexible and maintainable. In this article, we will dig into various aspects of the Composition API to better understand how it works and how it can be used in Vue 3 projects.

Traditional Options API vs. Composition API

In Vue 2, we use the Options API, which is a way to organize component code through option objects. While the Options API is easy to get started, it can make the code difficult to maintain and understand when dealing with complex components and large code bases. The Composition API is designed to solve these problems and provides a more flexible, well-organized, and maintainable way to build components.

The core concept of Composition API

The core concepts of the Composition API include the following key points:

1. setup function

The entry point of the Composition API issetupfunction. This function returns an object containing responsive states and methods for use by the component's templates and other functions. It accepts two parameters:propsandcontext。propsContains attributes passed from the parent component, andcontextContains some context information, such as global properties, slots, etc.

setup(props, context) {
  // Create and return responsive states and methods here}

2. ref and reactive

The Composition API providesrefandreactiveTwo functions for creating responsive data.refResponsive references used to create a single variable, andreactiveUsed to create responsive objects with multiple attributes.

const count = ref(0); // Create a responsive referenceconst data = reactive({ name: 'John', age: 30 }); // Create a responsive object

3. Responsive data and methods

The Composition API allows responsive data and methods to be organized together to improve the readability of your code. You cansetupCreate and return these data and methods in the function, and then use them in the template.

setup() {
  const count = ref(0); // Responsive counting  const increment = () => {
    ++;
  }; // Responsive method
  return { count, increment };
}

4. Life cycle hook

The Composition API retains the life cycle hooks in Vue 2, but they are exposed as functions rather than as properties of options objects. For example,createdThe hook is nowonCreatedfunction.

import { onCreated, ref } from 'vue';

export default {
  setup() {
    const count = ref(0);
    
    onCreated(() => {
      ('Component created');
    });

    return { count };
  }
};

5. Custom logical organization

The Composition API allows you to organize your code based on logical functions, not based on options. This makes it easier to put relevant data and methods together.

function useCounter() {
  const count = ref(0);
  const increment = () => {
    ++;
  };

  return { count, increment };
}

export default {
  setup() {
    const { count, increment } = useCounter();
    return { count, increment };
  }
};

Advantages of Composition API

Using the Composition API brings some of the following benefits:

1. Better organization and reuse

The Composition API allows the organization of relevant data and methods to make the code more readable and maintainable. This helps to better reuse logic and organize code.

2. More flexible logical reuse

You can more easily extract logic into reusable functions and share them across multiple components. This improves the maintainability of the code and reduces the need to repeatedly write similar code.

3. Better TypeScript support

The Composition API is better supported in TypeScript because it uses functional ways to define component logic, making it easier to add type annotations to components.

4. More intuitive life cycle hook

Lifecycle hooks in the Composition API are defined in the form of functions, which are more intuitive and easy to understand.

Summarize

The Composition API is a powerful feature in Vue 3 that brings better organizational code, better logic reuse, and better TypeScript support. It allows developers to build components more flexibly, making Vue 3 more powerful when dealing with complex components and large applications. If you are a Vue developer, it is recommended to learn and try it.

The above is a detailed article that will help you understand the use of Composition API in Vue3. For more information about the Vue3 Composition API, please follow my other related articles!