express+webpack中间件实现浏览器的实时刷新

express+webpack中间件实现浏览器的实时刷新

1、Express 是一个基于 Node.js 平台的极简、灵活的 web 应用开发框架。

2、webpack 是一个现代 JavaScript 应用程序的静态模块打包器(module bundler)。我们使用 webpack 处理应用程序时，它会递归地构建一个依赖关系图(dependency graph)，其中包含应用程序需要的每个模块，然后将所有这些模块打包成一个或多个 我们需要的目标文件。

3、我们使用的webpack中间是webapck-dev-middleware和webpack-hot-middleware

整个项目的目录如下

首先我们看一下webpack配置文件

let webpack = require('webpack');
module.exports = {
        //获取到入口文件并加上 webpack-hot-middleware 配置
    entry: ["./src/index.tsx","webpack-hot-middleware/client?path=/__webpack_hmr&timeout=20000&reload=true"],
    output: {
        //内存路径
        publicPath: "/dist/",
        filename: "bundle.js",
        //使用npm start不会再当前文件下生成dist/bundle.js  index.html文件中应用的内存中生成dist/bundle.js
        path: __dirname + "/dist"
    },
    module: {
        rules: [
            {
                test: /\.tsx?$/,
                use: 'ts-loader'
            }
        ]
    },
    resolve: {
        extensions: [".tsx", ".ts", ".js", ".json"]
    },
    plugins: [
        new webpack.optimize.OccurrenceOrderPlugin(),
        //HMR  该插件必不可少
        new webpack.HotModuleReplacementPlugin()
    ],
    //externals 会使 webpack将所有对"react"的导入转换成从React全局变量中加载（即window.React）
    // externals: {
    //     'react': 'React',
    //     'react-dom': 'ReactDOM'
    // }

}

server.js

let webpack = require("webpack");
let path = require("path");
let express = require("express");
let webpackDevMiddleWare = require("webpack-dev-middleware");
let webpackHotMiddleWare = require("webpack-hot-middleware");
let webpackConfig = require("./webpack.config.js");
let app = express();
let compiler = webpack(webpackConfig);
app.use(express.static(path.join(__dirname, "/")));
//webpack-dev-middleware输出的文件存在于内存中
//将编译器挂载给 webpack dev middleware 切它的publicPath要与webpack.config.js 的output.publicPath一致，不然找不到打包后的bundle文件
app.use(webpackDevMiddleWare(compiler, {
    publicPath: webpackConfig.output.publicPath
}));
//将编译器挂载给 webpack dev middleware
app.use(webpackHotMiddleWare(compiler, {
    heartbeat: 2000
}));
//所有请求 返回一个文件 即index.html
app.get("*", (req, res) => {
    res.sendFile(path.join(__dirname, "index.html"))
});
app.listen(8375, "localhost", () => {
    console.log('listening as http://localhost:8375')
})

package.json （npm init -y 生成）

{
  "name": "React-webpack-server",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "build": "./node_modules/.bin/webpack",
    "start":"node server.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "@types/react": "^16.3.14",
    "@types/react-dom": "^16.0.5",
    "express": "^4.16.3",
    "react": "^16.3.2",
    "react-dom": "^16.3.2",
    "ts-loader": "^3.5.0",
    "typescript": "^2.6.2",
    "webpack": "^3.12.0",
    "webpack-dev-middleware": "^2.0.6",
    "webpack-hot-middleware": "^2.22.2"
  }
}

tsconfig.json ( tsc –init 生成）

{
  "compilerOptions": {
    /* Basic Options */
    "target": "es5", /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */
    "module": "commonjs", /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
    "lib": [
      "es6",
      "dom",
      "dom.iterable"
    ], /* Specify library files to be included in the compilation. */
    // "allowJs": true,                       /* Allow javascript files to be compiled. */
    // "checkJs": true,                       /* Report errors in .js files. */
    "jsx": "react", /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
    // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
    "sourceMap": true, /* Generates corresponding '.map' file. */
    // "outFile": "./",                       /* Concatenate and emit output to single file. */
    "outDir": "./dist", /* Redirect output structure to the directory. */
    // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
    // "removeComments": true,                /* Do not emit comments to output. */
    // "noEmit": true,                        /* Do not emit outputs. */
    // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
    // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
    // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
    /* Strict Type-Checking Options */
    "strict": true, /* Enable all strict type-checking options. */
    // "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. */
    // "strictNullChecks": true,              /* Enable strict null checks. */
    // "strictFunctionTypes": true,           /* Enable strict checking of function types. */
    // "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
    // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
    // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
    /* Additional Checks */
    // "noUnusedLocals": true,                /* Report errors on unused locals. */
    // "noUnusedParameters": true,            /* Report errors on unused parameters. */
    // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
    // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
    /* Module Resolution Options */
    // "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
    "baseUrl": "./src", /* Base directory to resolve non-absolute module names. */
    // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
    // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
    // "typeRoots": [],                       /* List of folders to include type definitions from. */
    // "types": [],                           /* Type declaration files to be included in compilation. */
    // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
    //"esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
    // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
    /* Source Map Options */
    // "sourceRoot": "./",                    /* Specify the location where debugger should locate TypeScript files instead of source locations. */
    // "mapRoot": "./",                       /* Specify the location where debugger should locate map files instead of generated locations. */
    // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
    // "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
    /* Experimental Options */
    "experimentalDecorators": true, /* Enables experimental support for ES7 decorators. */
    "emitDecoratorMetadata": true, /* Enables experimental support for emitting type metadata for decorators. */
  },
  "include": [
    "src/**/*"
  ]
}

之后 我们npm start启动项目 修改Index.tsx或者App.tsx或者其他src下的tsx文件后保存浏览器就会自动刷新。

也可以 使用 npm run build 然后在浏览器直接打开index.html文件，不过这样每次修改文件后都需要使用npm run build命令生成新的bundle文件 然后手动刷新页面

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