第一步：安装HMR中间件：
npm install --save-dev webpack-hot-middleware
第二步：webpack配置中引入webpack对象
const webpack = require('webpack’);
第三步：增加devServer配置项：
hot: true
第四步：增加热模块替换插件：
new webpack.HotModuleReplacementPlugin()
注意：
1、ExtractTextPlugin插件可能会导致HMR无效。
另外，还可以通过使用web-dev-server —hotOnly参数来启用HMR。
参考官网链接：
https://webpack.js.org/guides/hot-module-replacement/
https://github.com/webpack-contrib/webpack-hot-middleware
React、Vue、Angular相关技术，请参考以下内容：
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React Hot Loader: Tweak react components in real time.
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Vue Loader: This loader supports HMR for vue components out of the box.
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Elm Hot Loader: Supports HMR for the Elm programming language.
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Angular HMR: No loader necessary! A simple change to your main NgModule file is all that's required to have full control over the HMR APIs.