为什么要搭建本地服务器?
Webpack watch
webpack-dev-server
- cnpm install --save-dev webpack-dev-server
- 注意,脚本是 "serve": "webpack serve"
webpack-dev-middleware 【了解】
webpack-dev-middleware的使用
认识模块热替换(HMR)
开启HMR
框架的HMR
React的HMR
- cnpm install -D @pmmmwh/react-refresh-webpack-plugin react-refresh
Vue的HMR
- cnpm install vue-loader vue-template-compiler -D
HMR的原理
HMR的原理图
webpack.config.js
const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const ReactRefreshWebpackPlugin = require('@pmmmwh/react-refresh-webpack-plugin');
const VueLoaderPlugin = require('vue-loader/lib/plugin');
module.exports = {
// watch: true,
mode: "development",
entry: "./src/index.js",
output: {
filename: "bundle.js",
path: path.resolve(__dirname, "./build")
},
// 专门为webpack-dev-server配置
devServer: {
hot: true
},
module: {
rules: [
{
test: /\.jsx?$/i,
use: "babel-loader"
},
{
test: /\.vue$/i,
use: "vue-loader"
},
{
test: /\.css/i,
use: [
"style-loader",
"css-loader"
]
}
]
},
plugins: [
new HtmlWebpackPlugin({
template: "./index.html"
}),
new ReactRefreshWebpackPlugin(),
new VueLoaderPlugin()
]
}
package.json
{
"name": "webpack_devserver",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"build": "webpack",
"watch": "webpack --watch",
"serve": "webpack serve"
},
"author": "",
"license": "ISC",
"devDependencies": {
"@babel/core": "^7.12.17",
"@babel/preset-env": "^7.12.17",
"@babel/preset-react": "^7.12.13",
"@pmmmwh/react-refresh-webpack-plugin": "^0.4.3",
"babel-loader": "^8.2.2",
"css-loader": "^5.0.2",
"html-webpack-plugin": "^5.2.0",
"react-refresh": "^0.9.0",
"style-loader": "^2.0.0",
"vue-loader": "^15.9.6",
"vue-template-compiler": "^2.6.12",
"webpack": "^5.23.0",
"webpack-cli": "^4.5.0",
"webpack-dev-server": "^3.11.2"
},
"dependencies": {
"express": "^4.17.1",
"react": "^17.0.1",
"react-dom": "^17.0.1",
"vue": "^2.6.12",
"webpack-dev-middleware": "^4.1.0"
}
}
index.js
/**
* 存在的问题:
* 问题一: 每次修改源代码之后, 我们都需要重新执行npm run build
* * 通过watch监听源代码的变化
*
* 目前的开发模式:
* 1.watch方案来监听文件的变化
* 2.通过live-server插件提供本地服务(当文件变化时,自动刷新页面)
* 效率并不是特别高:
* 1.对所有的源代码都重新进行编译
* 2.编译成功后,都会生成新的文件(文件操作 file system)
* 3.live-server属于VSCode插件(vim/webstorm) -> 不属于webpack给我们的解决方案
* 4.live-server每次都会重新刷新整个页面
*
* webpack-dev-server: hot module replacement(HMR)
*/
import "./math";
import React from 'react';
import ReactDom from 'react-dom';
import ReactApp from './App.jsx';
import Vue from 'vue';
import VueApp from './App.vue';
console.log("Hello 哈哈哈");
console.log("abc");
// 【module是全局对象。】
if (module.hot) {
module.hot.accept("./math.js", () => {
console.log("math模块发生了更新~");
});
}
// React的代码
ReactDom.render(<ReactApp/>, document.getElementById("app"));
// Vue的代码
new Vue({
render: h => h(VueApp)
}).$mount("#root");
App.vue
<template>
<div id="app">
<h2 class="title">{{ message }}</h2>
</div>
</template>
<script>
export default {
data() {
return {
message: "Hello 哈哈哈",
};
},
};
</script>
<style scoped>
.title {
color: blue;
}
</style>
App.jsx
import React, { Component } from "react";
class App extends Component {
constructor(props) {
super(props);
this.state = {
message: "Hello React",
};
}
render() {
return (
<div>
<h2>{this.state.message}</h2>
</div>
);
}
}
export default App;
babel.config.js
module.exports = {
presets: [
["@babel/preset-env"],
["@babel/preset-react"],
],
plugins: [
["react-refresh/babel"]
]
}
output的publicPath
devServer的publicPath
devServer的contentBase
hotOnly、host配置
port、open、compress
Proxy代理
changeOrigin的解析
historyApiFallback
resolve模块解析
确实文件还是文件夹
extensions和alias配置
目录结构
webpack.config.js
const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const ReactRefreshWebpackPlugin = require('@pmmmwh/react-refresh-webpack-plugin');
const VueLoaderPlugin = require('vue-loader/lib/plugin');
module.exports = {
// watch: true,
mode: "development",
entry: "./src/index.js",
output: {
filename: "bundle.js",
// 打包后的文件的输出目录
path: path.resolve(__dirname, "./build"),
// publicPath:在打包之后的静态资源前面进行一个路径的拼接,默认值是一个空字符串 【拼接:主机名 + publicPath + bundle.js】
// js/bundle 会拼接成 -> ./js/bundle.js,通过相对路径访问
// publicPath: "./"
// publicPath: "/abc"
},
// 专门为webpack-dev-server
// devServer为开发过程中, 开启一个本地服务
devServer: {
hot: true,
hotOnly: true,
// host: "0.0.0.0", // 经测试,不能通过 http://0.0.0.0:端口/ 进行访问
// port: 7777,
// open: true,
compress: true,
// 通过src与进入的静态资源会去配置的contentBase中查找【本地服务的路径是在"./why"】
contentBase: path.resolve(__dirname, "./why"),
watchContentBase: true, // abc.js代码改变后,自动刷新浏览器
// 开发环境中,devServer的publicPath 和 output的publicPath一致
// publicPath: "/abc",
proxy: {
// "/why": "http://localhost:8888"
"/why": {
// 映射,"/why"相当于"http://localhost:8888"
target: "http://localhost:8888",
pathRewrite: {
"^/why": ""
},
secure: false, // 支持https
changeOrigin: true // 如果服务器做了验证,就要设置为true
}
},
// historyApiFallback: true
historyApiFallback: {
rewrites: [
{from: /abc/, to: "/index.html"}
]
}
},
resolve: {
extensions: ['.wasm', '.mjs', '.js', '.json', '.jsx', '.ts', '.vue'],
alias: {
"@": path.resolve(__dirname, "./src"),
"pages": path.resolve(__dirname, "./src/pages")
}
},
module: {
rules: [
{
test: /\.jsx?$/i,
use: "babel-loader"
},
{
test: /\.vue$/i,
use: "vue-loader"
},
{
test: /\.css/i,
use: [
"style-loader",
"css-loader"
]
}
]
},
plugins: [
new HtmlWebpackPlugin({
template: "./index.html"
}),
new ReactRefreshWebpackPlugin(),
new VueLoaderPlugin()
]
}
index.js
import axios from 'axios';
import React from 'react';
import ReactDom from 'react-dom';
import ReactApp from './App.jsx';
import Vue from 'vue';
import VueApp from './App.vue';
import "./math";
console.log("Hello Coderwhy");
console.log("abc");
if (module.hot) {
module.hot.accept("./math.js", () => {
console.log("math模块发生了更新~");
});
}
// React的代码
ReactDom.render(<ReactApp/>, document.getElementById("app"));
// Vue的代码
new Vue({
render: h => h(VueApp)
}).$mount("#root");
// axios网络请求
// changeOrigin的解析:--> 因为使用了代码,默认情况下它的值是 http://localhost:8080,服务器接收来源的时候,如果不去对它做额外的配置,服务器会认为这次请求的来源就是 http://localhost:8080。本来应该是target对应的 "http://localhost:8888",但是做了代理,请求变成了http://localhost:8080。如果服务器没有对来源做校验,此时不会有问题。如果服务器为了防止通过代理的方式爬服务器的数据,做了校验,校验这次请求是不是在http://localhost:8888,发现是8080,不是8888,就不会返回数据,所以要改回成8888。用了第三方库,取代理服务器,把源换成target的值http://localhost:8888,服务器就会验证通过。
axios.get("http://localhost:8080/why/moment").then(res => {
console.log(res);
}).catch(err => {
console.log(err);
});