摘要：前言微前端理論篇微前端項目上一篇中，我們完成了項目的搭建，算是完成了整個微前端架構的一半工程了。項目項目是作為頁面的菜單顯示的，主要用于路由的控制。源碼地址源碼地址項目源碼地址微前端理論篇微前端項目微前端項目

????????微前端 —— 理論篇
????????微前端 —— portal項目
????????上一篇中，我們完成了portal項目的搭建，算是完成了整個微前端架構的一半工程了?，F在開始新建我們的業務小應用。

????????menu項目是作為頁面的菜單顯示的，主要用于路由的控制。
????????項目的結構如下：

????????接下來就開始實現它吧。

新建項目文件夾menu，在根目錄執行npm init -y

安裝相關依賴，由于react相關的幾個依賴已經在portal項目中抽離出來，因此我們這不需要安裝了。

???????? package.js文件內容如下：

    {
      "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文件夾，在src文件夾下創建components文件夾，在components文件夾中新建文件Menu.js,內容如下：

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

????????現在我們已經實現了菜單的頁面代碼。在src目錄下新建文件root.component.js，引入導出Menu組件

    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目錄下新建文件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目錄下新建文件menu.js，用于組件的注冊

    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;
    }

????????最后編寫webpack配置文件，在項目根目錄下創建文件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.*/,
      ],
    };

????????公共依賴就別多帶帶打包了
????????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項目的源碼大概就這些

3.project1
????????project1項目也是通過react框架實現的，主要是實現了不同路由匹配不同頁面，最后運行打包的時候，暴露出一個js文件，共portal項目調用。詳細的就不闡述了，跟menu項目大同小異，也就只是頁面代碼不一樣。

????????menu源碼地址
????????project1源碼地址
????????項目源碼地址

????????微前端 —— 理論篇
????????微前端 —— portal項目
????????微前端 —— project2項目（VUE）