# 八.热更新

# 1.安装

package.json

{
  "name": "8.hotUpdate",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "build": "webpack",
    "dev": "webpack-dev-server",
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@babel/core": "^7.4.0",
    "@babel/preset-env": "^7.4.2",
    "@babel/preset-react": "^7.0.0",
    "babel-loader": "^8.0.5",
    "html-webpack-plugin": "^3.2.0",
    "webpack": "^4.29.6",
    "webpack-cli": "^3.3.0",
    "webpack-dev-server": "^3.2.1"
  },
  "dependencies": {
    "jquery": "^3.3.1",
    "moment": "^2.24.0"
  }
}

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# 2.文件

src/index.js

import str from "./source"
console.log(str)
if (module.hot) {
  module.hot.accept("./source", () => {
    let a = require("./source")
    console.log(a)
  })
}

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src/source.js

export default "1sa23";

# 3.配置

webpack.config.js

let path = require("path")
let HtmlWebpackPlugin = require("html-webpack-plugin")
let webpack = require("webpack")
module.exports = {
  mode: "development",
  entry: {
    index: "./src/index.js",
  },
  devServer: {
    hot: true,
  },
  output: {
    filename: "[name].js",
    path: path.resolve(__dirname, "dist"),
  },
  plugins: [
    new HtmlWebpackPlugin({
      template: "./public/index.html",
    }),
    new webpack.NamedModulesPlugin(), //打印更新的模块路径
    new webpack.HotModuleReplacementPlugin(), // 热更新
  ],
  module: {
    noParse: /jquery/, //不去解析jquery中的依赖库
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        include: path.resolve("src"),
        use: {
          loader: "babel-loader",
          options: {
            presets: ["@babel/preset-env", "@babel/preset-react"],
          },
        },
      },
    ],
  },
}

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# 4.运行

npm run dev

修改 source 里面的内容，可以看到页面没有刷新但是内容更新了完整代码 (opens new window)

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