This time I will bring you the hook function of Vue beforeEnter. What are the precautions for using the hook function of Vue beforeEnter? The following is a practical case, let's take a look.
Why do we need to create our own beforeEnter hook function?
Look at the problem scenario: There is a word list page in the project. Each cell will note whether the word has been mastered. Click on the cell to enter the details page, where you can learn the word and mark it. Whether the word is mastered, and you can also learn other words by clicking the forward and back buttons on the details page. So when I click return, the word list should show the latest status of all word users.The final page relationship is like this:
wordListPage ——> wordDetail (learn a series of words, exit) ——> wordListPage (refresh words List) For the above scenario, it is not possible to use the Vuelife cycle function, because Vue’s life cycle functions such as: beforeCreate, created, beforeMounted, mounted, etc., can only be used when the component is initialized. It will be called only when the component (VM instance) comes from the cache (such as $route.go(-1), keep-alive), the life cycle function will no longer be called. Therefore, when I return to the list page from the word details page, I cannot find a suitable period to start the dataupdate. Therefore, the above scenario cannot be handled well.
Of course, the above scenarios are relatively rare, but the existence of the beforeEnter hook function is still necessary.Construct the beforeEnter hook function
Dependent knowledge points:- Routing: vue-router
- Mixin: mixin
- Central
EventBus
1. Create a central event bus
For the central event bus, a simple understanding is to create a public Vue instance (EventBus) and use the same instance in different places to trigger EventBus.$emit('demo' ) message, use a public Vue instance to listen to EventBus.$on('demo',() => {}) where you want to listen to the event. To put it bluntly, there is such a public component that sends messages to different places and listens for messages in different places. So the sending and receiving of messages is implemented by itself, so we call it the central event bus. The code is as follows: libs/EventBus.jsimport Vue from 'vue'; const EventBus = new Vue(); export default EventBus;Let’s see how to use it
2. Routing hook function beforeEach
Through the beforeEach hook function, the beforeEnter event of the corresponding component is triggered when the route is switched. The code is as follows: router/index.jsimport EventBus from '@/libs/EventBus'; router.beforeEach((to, from, next) => { //如:EventBus.$emit('homeBeforeEnter'); EventBus.$emit(to.name + 'BeforeEnter'); if (to.matched.some(route => route.meta.isAuth)) { ... next() } else { next() } })
3. Create a global mix-in object
Here to implement the monitoring of route switching events and component instance hooks Triggering of function beforeEnter. libs/beforeEnterMixin.jsimport EventBus from './EventBus'; export default { beforeCreate() { //获取当前路由名称,与前面使用to.name对应 let vmName = this.$route.name; if (!vmName) { return; } // 当组件初始化时,先触发一次,后续将不再调用 this.$options.beforeEnter(); const beforeEnter = vmName + 'BeforeEnter'; //监听路由切换时触发的...BeforeEnter事件 //通过this.$options获取到实例中的beforeEnter钩子函数 //监听到...BeforeEnter事件后,触发钩子函数beforeEnter调用 EventBus.$on(beforeEnter, this.$options.beforeEnter); }, //该函数在这里只作为占位,没有实际意义 beforeEnter() {} };For this mixin object, it is feasible to use global or local mixin. Global mixing: main.js
import beforeEnterMixin from '@/libs/beforeEnterMixin'; Vue.mixin(beforeEnterMixin);
4. Use in components
For example: home.vue<template> <p> 首页 </p> </template> <script> export default { beforeEnter() { console.log('首页 beforeEnter...'); }, created() { console.log('首页 created...') } } </script>At this point, our beforeEnter is complete. You can make a demo to test it yourself. Currently, I use it in many projects. I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website! Recommended reading:
Detailed explanation of how to implement tabs and switching functions in vue
Detailed explanation of the use of $refs in vue
The above is the detailed content of Vue+beforeEnter uses hook function. For more information, please follow other related articles on the PHP Chinese website!

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

Python and JavaScript have their own advantages and disadvantages in terms of community, libraries and resources. 1) The Python community is friendly and suitable for beginners, but the front-end development resources are not as rich as JavaScript. 2) Python is powerful in data science and machine learning libraries, while JavaScript is better in front-end development libraries and frameworks. 3) Both have rich learning resources, but Python is suitable for starting with official documents, while JavaScript is better with MDNWebDocs. The choice should be based on project needs and personal interests.

The shift from C/C to JavaScript requires adapting to dynamic typing, garbage collection and asynchronous programming. 1) C/C is a statically typed language that requires manual memory management, while JavaScript is dynamically typed and garbage collection is automatically processed. 2) C/C needs to be compiled into machine code, while JavaScript is an interpreted language. 3) JavaScript introduces concepts such as closures, prototype chains and Promise, which enhances flexibility and asynchronous programming capabilities.

Different JavaScript engines have different effects when parsing and executing JavaScript code, because the implementation principles and optimization strategies of each engine differ. 1. Lexical analysis: convert source code into lexical unit. 2. Grammar analysis: Generate an abstract syntax tree. 3. Optimization and compilation: Generate machine code through the JIT compiler. 4. Execute: Run the machine code. V8 engine optimizes through instant compilation and hidden class, SpiderMonkey uses a type inference system, resulting in different performance performance on the same code.

JavaScript's applications in the real world include server-side programming, mobile application development and Internet of Things control: 1. Server-side programming is realized through Node.js, suitable for high concurrent request processing. 2. Mobile application development is carried out through ReactNative and supports cross-platform deployment. 3. Used for IoT device control through Johnny-Five library, suitable for hardware interaction.

I built a functional multi-tenant SaaS application (an EdTech app) with your everyday tech tool and you can do the same. First, what’s a multi-tenant SaaS application? Multi-tenant SaaS applications let you serve multiple customers from a sing


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.

Dreamweaver CS6
Visual web development tools

WebStorm Mac version
Useful JavaScript development tools

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

Notepad++7.3.1
Easy-to-use and free code editor