前言
由于公司当前项目过于臃肿，打包速度越来越慢，同时在每次代码合并时，会出现非常多的冲突。因此，希望找到一种方式，来减小项目体积，又不影响现有代码的方式。在寻找过程中，发现微前端是一种很不错的方式，技术无关，同时可以分开部署，简直完美。
目前主流的微前端方式，主要有iframe，single-spa，qiankun，micro-app以及webpack5的module ferderation等。鉴于我们当前项目是以webpack4为主，首先排除了module ferderation。micro-app是京东开源的微前端框架，基于shadowdom实现，shadowdom容易出现一些问题，如iconfront显示问题，因此跳过。qiankun是蚂蚁集团基于single-spa进行的封装，但基于更喜欢自己封装，遂最终选择了single-spa。
single-spa
single-spa实现原理：首先对微前端路由进行注册，使用single-spa充当微前端加载器，并做为项目单一入口来接受全部页面URL的访问，根据页面URL与微前端的匹配关系，选择加载对应的微前端模块，再由该微前端模块进行路由响应URL，即微前端模块中路由找到相应的组件，渲染页面内容。
single-spa实现过程
- 基座项目
基于vue的基座项目,使用vue-cli创建基座项目
vue create micro-front-cli-root-config
- 首先在dom创建节点挂载子项目，子项目注册后即可挂载在基座项目
- 微前端子应用注册
子应用打包成umd包，通过script加载，再使用single-spa的registerApplication api进行注册应用，最终调用start方法启动子项目
// appConfig
const apps = [{
host: 'http://localhost:9001',
projectName: 'singleVue',
activeWhen: location => location.pathname.startsWith('/vue'),
bundle: 'app'
}]
export default apps
import { registerApplication, start } from 'single-spa'; //导入single-spa
import axios from 'axios'
import AppConfig from './appConfig'
/**
* @name 加载异步js
* @description 一个promise同步方法。可以代替创建一个script标签，然后加载服务
* @param {*} url
* @returns
*/
const runScript = async (url) => {
return new Promise((resolve, reject) => {
const script = document.createElement('script');
script.src = url;
script.onload = () => {
resolve()
};
script.onerror = (err) => {
console.log(err)
reject()
};
const firstScript = document.getElementsByTagName('script')[0];
firstScript.parentNode.insertBefore(script, firstScript);
});
};
const isObject = (obj) => {
return Object.prototype.toString.call(obj) === '[object Object]'
}
/**
* 加载子应用
* @param {*} host
* @param {*} globalVar
* @returns
*/
const loadApp = (host, globalVar, bundle) => {
return async () => {
await getManifest(`${host}/asset-manifest.json`, bundle, host)
return window[globalVar]
}
}
/**
* @description 加载子应用
* @param {*} url stats-webpack-plugin或者webpack-manifest-plugin插件生成的manifest文件
* @param {*} bundle
* @param {*} host 子应用host+port
*/
const getManifest = async (url, bundle, host) => {
const { data } = await axios.get(url);
const { entrypoints } = data;
let assets = []
if (Array.isArray(entrypoints)) {
assets = entrypoints
} else {
assets = entrypoints[bundle].assets
assets = assets.map(obj => {
if (isObject(obj)) {
return obj.name
}
return obj
})
}
for (let i = 0; i < assets.length; i++) {
await runScript(`${host}/${assets[i]}`)
}
}
AppConfig.forEach(app => {
// 注册微服务（子应用）
registerApplication({
name: app.projectName,
app: loadApp(app.host, app.projectName, app.bundle), // 子应用为umd包，挂载在window下
activeWhen: app.activeWhen, // 当url匹配时展示子应用
customProps: app.customProps
})
})
start(); // 启动
Vue子项目改造
Vue2.0
import Vue from 'vue'
import App from './App.vue'
import singleSpaVue from "single-spa-vue";
Vue.config.productionTip = false
// el 为子项目待挂载到父项目的DOM节点
const vueOptions = {
el: "#singleVue2",
render: h => h(App)
};
// 主应用注册成功后会在window下挂载singleSpaNavigate方法
// 为了独立运行，避免子项目页面为空，
// 判断如果不在微前端环境下进行独立渲染html
if (!window.singleSpaNavigate) {
new Vue({
render: h => h(App),
}).$mount('#app')
}
const vueLifecycles = singleSpaVue({
Vue,
appOptions: vueOptions,
handleInstance(app, props) {
Vue.prototype.$eventBus = props.EventBus
}
});
export const bootstrap = vueLifecycles.bootstrap; // 启动时
export const mount = vueLifecycles.mount; // 挂载时
export const unmount = vueLifecycles.unmount; // 卸载时
export default vueLifecycles;
Vue3.0
import { h, createApp } from 'vue'
import singleSpaVue from 'single-spa-vue'
import App from './App.vue'
import router from './router'
const appOptions = {
el: '#singleVue', // 若提供el属性，则挂载在el上，否则是，single-spa-application:${name}上，name为基座项目注册子应用设置的name
render() {
return h(App, {
// single-spa props are available on the "this" object. Forward them to your component as needed.
// https://single-spa.js.org/docs/building-applications#lifecycle-props
// if you uncomment these, remember to add matching prop definitions for them in your App.vue file.
/*
name: this.name,
mountParcel: this.mountParcel,
singleSpa: this.singleSpa,
*/
name: this.name,
singleSpa: this.singleSpa,
EventBus: this.EventBus,
})
},
}
if (!window.singleSpaNavigate) {
createApp(App).use(router).mount('#app')
}
const vueLifecycles = singleSpaVue({
createApp,
appOptions,
handleInstance(app) {
app.use(router)
},
})
export const bootstrap = [vueLifecycles.bootstrap]
export const mount = [vueLifecycles.mount]
export const unmount = [vueLifecycles.unmount]
export default vueLifecycles
修改vue.config.js
const StatsPlugin = require('stats-webpack-plugin')
const projectName = 'singleVue'
module.exports = {
publicPath: '//localhost:9001',
css: {
extract: false
},
configureWebpack: {
output: {
library: {
name: projectName, // 导出名称
type: 'umd' // 挂载目标,window.singleVue
}
},
devServer: {
port: '9001',
headers: {
'Access-Control-Allow-Origin': '*'
},
allowedHosts: 'all'
},
plugins: [
new StatsPlugin('asset-manifest.json', {
chunkModules: false,
entryPoints: true,
source: false,
chunks:false,
modules: false,
assets: false,
children: false,
exclude: [/node_modules/]
})
]
},
}
React子项目改造
当前改造基于React18.1,项目使用create-react-app创建
import React from 'react';
import ReactDOM from 'react-dom/client';
import { BrowserRouter } from "react-router-dom";
import { Provider } from 'react-redux'
import store from './store'
import './index.css';
import App from './App';
import reportWebVitals from './reportWebVitals';
import singleSpaReact from 'single-spa-react';
function rootComponent () {
return (
)
}
if (!window.singleSpaNavigate) {
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(rootComponent());
}
// If you want to start measuring performance in your app, pass a function
// to log results (for example: reportWebVitals(console.log))
// or send to an analytics endpoint. Learn more: https://bit.ly/CRA-vitals
reportWebVitals();
const lifecycles = singleSpaReact({
React,
ReactDOM,
rootComponent: rootComponent,
errorBoundary(err, info, props) {
// Customize the root error boundary for your microfrontend here.
return null;
},
renderType: 'createRoot',
domElementGetter: () => document.getElementById('singleReact')
})
export const bootstrap = [lifecycles.bootstrap]
export const mount = [lifecycles.mount]
export const unmount = [lifecycles.unmount]
// export const { bootstrap, mount, unmount } = lifecycles;
修改webpack配置，使用react-app-rewired，customize-cra修改配置
const { override, addWebpackPlugin, overrideDevServer } = require('customize-cra')
const StatsPlugin = require('stats-webpack-plugin')
const projectName = 'singleReact'
const customizePlugin = () => config => {
config.output.publicPath = 'http://localhost:9003/'
config.output.library = projectName
config.output.libraryTarget = 'umd'
return config
}
module.exports = {
webpack: override(
addWebpackPlugin(
new StatsPlugin('asset-manifest.json', {
chunkModules: false,
entryPoints: true,
source: false,
chunks: false,
modules: false,
assets: false,
children: false,
exclude: [/node_modules/]
})
),
customizePlugin()
),
devServer: overrideDevServer(
config => {
config.port = '9003'
config.headers = config.headers || {}
config.headers['Access-Control-Allow-Origin'] = '*'
return config
}
)
}
基座项目与子项目的通信
single-spa官网推荐了两种方式，一种是rxjs,另一种是使用自定义Event的方式。目前我采用了rxjs,实现类似EventBus的方式来通信。
import { ReplaySubject, filter, map } from 'rxjs'
class EventBus {
constructor() {
this.subject$ = new ReplaySubject()
}
emit(event) {
this.subject$.next(event)
}
on(eventName, action) {
return this.subject$.pipe(
filter(e => e.name === eventName),
map((e) => e.data)
).subscribe(action)
}
}
export default EventBus
使用方式
// 下发消息
EventBus.emit({name: 'msgFromRoot', data: 'vue3 root msg'})
// 接收消息
EventBus?.value?.on('msgFromRoot', data => {
console.log('vue:', data)
})
样式隔离
可以通过postcss-selector-namespace或者postcss-prefix-selector插件来为所有样式添加前缀。
项目地址
完整源码请查看microfront