Detailed explanation of global functions in Vue3: applications that enable more convenient global method calls

Detailed explanation of global functions in Vue3: Applications that enable more convenient global method calls

Vue3 is the latest version of the Vue.js framework, and its new design also introduces new features. Among them, global functions are a very noteworthy new feature of Vue3 compared to Vue2. The introduction of global functions makes calling global methods more convenient and efficient, and can also effectively reduce the need to write repeated code. This article will introduce the global functions in Vue3 in detail and illustrate its specific applications through relevant examples.

Definition of global functions in Vue3

Global functions refer to functions that can be defined outside any component in Vue3 and can be shared and accessed by all components. In Vue3, we can define global functions through the following methods:

app.config.globalProperties.$helper = function() {
    // 方法体
};

Among them, app is the Vue application instance, config is the global configuration object, through globalPropertiesYou can define global properties and methods. At this time, we define a global function named $helper.

It is worth noting that in Vue2, the global function is usually defined in main.js, but in Vue3, the global function should be in the callback function of createApp defined, otherwise an error will occur.

With the global function, we can easily call the function in any component. The specific usage is as follows:

<template>
  <div>{{ $helper() }}</div>
</template>

Therefore, once the global function is defined, we can call it in all components It is very convenient to call it through $helper() in the component.

In addition, we can also define multiple global functions, just declare different function names separately.

Application of global functions in Vue3

Now that we understand how global functions are defined, we will use some specific application cases to illustrate their specific usage:

1. Data formatting

In Vue3, we can format data through global functions. For example, in our front-end development, we often encounter situations where we need to convert time into string format. At this time, we can define a global function to handle it:

app.config.globalProperties.$formatDate = function(date) {
    const year = date.getFullYear();
    const month = date.getMonth();
    const day = date.getDay();
    return `${year}-${month}-${day}`;
};

In this way, we can use $ formatDate() method to implement formatting time operations.

2. Universal method encapsulation

Global functions can also be used to encapsulate universal methods. For example, Axios is often used in development to send network requests. We can define a global function to encapsulate it:

app.config.globalProperties.$axios = function(config) {
    return axios(config).then(response => {
        return response.data;
    }).catch(error => {
        console.log(error);
    });
};

In this way, we can pass $axios() in all components method to send network requests, and can also effectively reduce the repeated writing of network request code.

3. Shared method calls

In Vue3, since component instances are no longer exposed on the global object, when accessing methods in other components, you need to pass parameters or use events to fulfill. Global functions can solve this problem.

For example, inside a component, we need to call a method inside another component:

// 通过 $root 调用父曾内部的方法
this.$root.$refs['app-header'].$toggleSidebar();

Although this method is feasible, it is too cumbersome. We can define a global function to achieve more convenient method calling:

app.component('AppHeader', {
    mounted() {
        app.config.globalProperties.$toggleSidebar = this.toggleSidebar;
    },
    methods: {
        toggleSidebar() {
            // 方法体
        }
    }
})

In this way, in any component, we can easily call the parent component through the $toggleSidebar() method Internal functions.

Summary

Global functions are a very important new feature of Vue3. It can effectively reduce the need to write repeated code while making method calls more convenient and efficient. In Vue3 development, we can use global functions to perform a series of operations such as data formatting, general method encapsulation, and shared method calling, which help us improve development efficiency and reduce redundant code.

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