摘要：前言微前端理论篇微前端项目上一篇中，我们完成了项目的搭建，算是完成了整个微前端架构的一半工程了。项目项目是作为页面的菜单显示的，主要用于路由的控制。源码地址源码地址项目源码地址微前端理论篇微前端项目微前端项目

        微前端 —— 理论篇
        微前端 —— portal项目
        上一篇中，我们完成了portal项目的搭建，算是完成了整个微前端架构的一半工程了。现在开始新建我们的业务小应用。

        menu项目是作为页面的菜单显示的，主要用于路由的控制。
        项目的结构如下：

        接下来就开始实现它吧。

新建项目文件夹menu，在根目录执行npm init -y

安装相关依赖，由于react相关的几个依赖已经在portal项目中抽离出来，因此我们这不需要安装了。

         package.js文件内容如下：

    {
      "name": "menu",
      "version": "1.0.0",
      "description": "",
      "main": "index.js",
      "scripts": {
        "test": "echo "Error: no test specified" && exit 1",
        "start": "webpack-dev-server --config ./webpack.dev.js --port 8235",
        "build": "webpack --config ./webpack.config.js -p"
      },
      "keywords": [],
      "author": "",
      "license": "ISC",
      "dependencies": {
        "antd": "^3.20.7",
        "babel-plugin-import": "^1.12.0",
        "copy-webpack-plugin": "^5.0.4",
        "react-router": "4.3.1",
        "react-router-dom": "4.3.1",
        "single-spa-react": "2.8.1",
        "@reach/router": "1.2.1"
      },
      "devDependencies": {
        "@babel/core": "7.0.0",
        "@babel/plugin-proposal-class-properties": "7.0.0",
        "@babel/plugin-proposal-decorators": "7.1.0",
        "@babel/plugin-proposal-object-rest-spread": "7.0.0",
        "@babel/plugin-syntax-dynamic-import": "^7.0.0",
        "@babel/preset-env": "7.0.0",
        "@babel/preset-react": "7.0.0",
        "autoprefixer": "9.1.5",
        "babel-core": "6.26.3",
        "babel-loader": "8.0.0",
        "clean-webpack-plugin": "0.1.19",
        "css-loader": "1.0.0",
        "postcss-loader": "3.0.0",
        "style-loader": "0.23.0",
        "webpack": "4.17.1",
        "webpack-cli": "3.1.0",
        "webpack-dev-server": "^3.1.14"
      }
    }

        新建src文件夹，在src文件夹下创建components文件夹，在components文件夹中新建文件Menu.js,内容如下：

    import React from "react"
    import {Menu, Icon} from "antd"
    import { Link } from "@reach/router"
    const MenuItem = Menu.Item
    
    export default class Menu_ extends React.Component {
        render () {
            return (
                

                    
menu!
                    
                        
                            
                            主页
                        
                        
                            
                            页面1
                        
                        
                            
                            页面2
                        
                        
                            
                            页面3
                        
                        
                            
                            页面4
                        
                    
                
            )
        }
    }
    
    const menuStyle = {
        display: "inline-block",
        position: "fixed",
        width: "300px",
        height: "100%"
    }

        现在我们已经实现了菜单的页面代码。在src目录下新建文件root.component.js，引入导出Menu组件

    import React from "react"
    import { BrowserRouter, Route, Switch, Redirect } from "react-router-dom"
    import Menu from "./components/Menu"
    
    export default class Root extends React.Component {
    
      state = {
        hasError: false
      }
    
      componentDidCatch (error, info) {
        this.setState({hasError: true})
      }
    
      render () {
        return (
          
        )
      }
    }

        在src目录下新建文件set-public-path.js

    // For lazy loading within an application to work you need to set webpack"s public path
    // basically webpack"s internal module system always looks for code-splits (modules) at the root
    export default function setPublicPath() {
      return Promise.all([getUrl()]).then(values => {
        const [url] = values
        const webpackPublicPath = url.slice(0, url.lastIndexOf("/") + 1)
    
        __webpack_public_path__ = webpackPublicPath
        return true
      })
    }
    
    function getUrl () {
      return window.System.resolve("@portal/menu")
    }

        在src目录下新建文件menu.js，用于组件的注册

    import React from "react"
    import ReactDOM from "react-dom"
    import singleSpaReact from "single-spa-react"
    import { property } from "lodash"
    import setPublicPath from "./set-public-path.js"
    
    const reactLifecycles = singleSpaReact({
      React,
      ReactDOM,
      loadRootComponent: () => import(/* webpackChunkName: "people-app" */"./root.component.js").then(property("default")),
      domElementGetter,
    })
    
    export const bootstrap = [
      () => {
        return setPublicPath()
      },
      reactLifecycles.bootstrap,
    ]
    
    export const mount = [
      reactLifecycles.mount,
    ]
    
    export const unmount = [
      reactLifecycles.unmount,
    ]
    
    export const unload = [
      reactLifecycles.unload,
    ]
    
    function domElementGetter() {
      let el = document.getElementById("menu");
      if (!el) {
        el = document.createElement("div");
        el.id = "menu";
        document.body.appendChild(el);
      }
    
      return el;
    }

        最后编写webpack配置文件，在项目根目录下创建文件webpack.config.js、webpack.dev.js


        webpack.config.js

    /* eslint-env node */
    const webpack = require("webpack")
    const path = require("path");
    const CleanWebpackPlugin = require("clean-webpack-plugin");
    const CopyWebpackPlugin = require("copy-webpack-plugin");
    
    module.exports = {
      entry: path.resolve(__dirname, "src/menu.js"),
      output: {
        filename: "menu.js",
        library: "menu",
        libraryTarget: "amd",
        path: path.resolve(__dirname, "build/menu"),
      },
      mode: "production",
      module: {
        rules: [
          {parser: {System: false}},
          {
            test: /.js?$/,
            exclude: [path.resolve(__dirname, "node_modules")],
            loader: "babel-loader",
          },
          {
            test: /.css$/,
            exclude: [path.resolve(__dirname, "node_modules")],
            use: [
              "style-loader",
              {
                loader: "css-loader",
                options: {
                  modules: true,
                  localIdentName: "[path][name]__[local]",
                },
              },
              {
                loader: "postcss-loader",
                options: {
                  plugins() {
                    return [
                      require("autoprefixer")
                    ];
                  },
                },
              },
            ],
          },
          {
            test: /.css$/,
            include: [path.resolve(__dirname, "node_modules")],
            exclude: [/.krem.css$/],
            use: ["style-loader", "css-loader"],
          },
        ],
      },
      resolve: {
        modules: [
          __dirname,
          "node_modules",
        ],
      },
      plugins: [
        new CleanWebpackPlugin(["build/menu"]),
        new CopyWebpackPlugin([
          {from: path.resolve(__dirname, "src/Menu.js")}
        ]),
      ],
      devtool: "source-map",
      externals: [
        /^@portal/*/,
        /^lodash$/,
        /^single-spa$/,
        /^rxjs/?.*$/,
        /^react$/,
        /^react/lib.*/,
        /^react-dom$/,
        /.*react-dom.*/,
      ],
    };

        公共依赖就别多带带打包了
        webpack.dev.js

    /* eslint-env node */
    const config = require("./webpack.config.js");
    const webpack = require("webpack");
    
    config.plugins.push(new webpack.NamedModulesPlugin());
    config.plugins.push(new webpack.HotModuleReplacementPlugin());
    config.devServer = {
      headers: {
        "Access-Control-Allow-Origin": "*",
      },
    }
    
    config.mode = "development"
    
    module.exports = config;

        menu项目的源码大概就这些

3.project1
        project1项目也是通过react框架实现的，主要是实现了不同路由匹配不同页面，最后运行打包的时候，暴露出一个js文件，共portal项目调用。详细的就不阐述了，跟menu项目大同小异，也就只是页面代码不一样。

        menu源码地址
        project1源码地址
        项目源码地址

        微前端 —— 理论篇
        微前端 —— portal项目
        微前端 —— project2项目（VUE）