基于webpack4.X从零搭建React脚手架的方法步骤
项目初始化
$ npm init
安装webpack
本次创建是基于webpack4
$ npm install --save-dev
新建webpack配置文件
在根目录创建build文件夹,添加一个js文件,命名为webpack.base.conf.js
// webpack.base.conf.js 文件 const path = require('path'); const DIST_PATH = path.resolve(__dirname, '../dist'); module.exports = { entry: { app: './app/index.js' }, output: { filename: "js/bundle.js", path: DIST_PATH } };
使用merge的方式来组织webpack基础配置和不同环境的配置
先安装webpack-merge:
$ npm install --save-dev webpack-merge
在build文件夹中再添加一个js文件,命名为 webpack.prod.conf.js
// webpack.prod.conf.js 文件 const merge = require('webpack-merge'); const baseWebpackConfig = require('./webpack.base.conf'); module.exports = merge(baseWebpackConfig, { mode: 'production' });
在根目录下创建app目录,然后创建index.js文件
var element =document.getElementById('root'); element.innerHTML = 'hello, world!';
在根目录创建一个public文件夹,然后新建一个index.html文件
// index.html <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>从零开始搭建react工程</title> </head> <body> <div id="root"></div> <script src="../dist/js/bundle.js"></script> </body> </html>
当前项目目录树
|- /app |- index.js |- /node_modules |- /public |- index.html |- /build |- webpack.base.conf.js |- webpack.prod.conf.js |- package.json |- package-lock.json
安装webpack-cli
webpack 4.0 版本之后的webpack,已经将webpack命令工具迁移到webpack-cli模块了,需要安装 webpack-cli
$ npm install --save-dev webpack-cli
package.json文件 scripts属性配置一个build命令
其值为:webpack --config build/webpack.prod.conf.js,以下是scripts的相关代码
// package.json "scripts": { "build": "webpack --config build/webpack.prod.conf.js", "test": "echo \"Error: no test specified\" && exit 1" },
安装React
$ npm install --save react react-dom
修改app目录下的index.js的代码
import React from "react"; import ReactDom from "react-dom"; ReactDom.render( <h1>hello, world!</h1>, document.getElementById("root") );
注意 import 属于ES6规范,因此需要转译ES2015+的语法,安装并配置 babel 以及相关依赖
$ npm install --save-dev babel-loader babel-core babel-preset-env babel-preset-react
根目录创建.babelrc文件,配置presets.
{ "presets": [ [ "env", { "targets": { "browsers": [ "> 1%", "last 5 versions", "ie >= 8" ] } } ], "react" ] }
修改webpack.base.conf.js文件
// webpack.base.conf.js const path = require('path'); const APP_PATH = path.resolve(__dirname, '../app'); const DIST_PATH = path.resolve(__dirname, '../dist'); module.exports = { entry: { app: './app/index.js' }, output: { filename: 'js/bundle.js', path: DIST_PATH }, module: { rules: [ { test: /\.js?$/, use: "babel-loader", include: APP_PATH } ] } };
运行 npm run build
添加插件
public下的index.html本该自动添加到dist目录,并且引用资源自动加载到该文件,通过html-webpack-plugin实现这一步
$ npm install html-webpack-plugin --save-dev
webpack.prod.conf.js中配置plugins属性
const merge = require('webpack-merge'); const baseWebpackConfig = require('./webpack.base.conf.js'); const HtmlWebpackPlugin = require('html-webpack-plugin'); module.exports = merge(baseWebpackConfig, { mode: 'production', plugins: [ new HtmlWebpackPlugin({ template: 'public/index.html', inject: 'body', minify: { removeComments: true, collapseWhitespace: true, removeAttributeQuotes: true }, }) ] });
删除 index.html 中手动引入的 script 标签
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>从零开始搭建react工程</title> </head> <body> <div id="root"></div> </body> </html>
重新编译查看 npm run build 浏览器打开查看目录 dist 下的 index.html
以上步骤都成功的前提下继续走下一步
生成的文件名添加Hash值,目的是解决缓存问题
修改webpack.prod.conf.js,mode: 'production', 增加以下代码
// webpack.prod.conf.js output: { filename: "js/[name].[chunkhash:16].js", },
生成前需要清理之前项目生成的文件,因为由于文件名的改变如果不删除会一直增加
安装插件 clean-webpack-plugin
$ npm install --save-dev clean-webpack-plugin
修改 webpack.prod.conf.js
// webpack.prod.conf.js const merge = require('webpack-merge'); const baseWebpackConfig = require('./webpack.base.conf.js'); const HtmlWebpackPlugin = require('html-webpack-plugin'); const CleanWebpackPlugin = require('clean-webpack-plugin'); module.exports = merge(baseWebpackConfig, { mode: 'production', output: { filename: "js/[name].[chunkhash:16].js", }, plugins: [ new HtmlWebpackPlugin({ template: 'public/index.html', inject: 'body', minify: { removeComments: true, collapseWhitespace: true, removeAttributeQuotes: true }, }), new CleanWebpackPlugin(['../dist'], { allowExternal: true }) ] });
公共代码与业务代码分离
修改 webpack.base.conf.js 的 entry 入口属性,抽出框架代码
entry: { app: './app/index.js', framework: ['react','react-dom'], },
修改webpack.prod.conf.js,增加以下代码,目的是分离框架代码和业务代码
虽然上面步骤抽出框架代码生成两个文件,但是app.js还是包含框架代码
optimization: { splitChunks: { chunks: "all", minChunks: 1, minSize: 0, cacheGroups: { framework: { test: "framework", name: "framework", enforce: true } } } }
cacheGroups对象,定义了需要被抽离的模块
其中test属性是比较关键的一个值,他可以是一个字符串,也可以是正则表达式,还可以是函数。如果定义的是字符串,会匹配入口模块名称,会从其他模块中把包含这个模块的抽离出来
name是抽离后生成的名字,和入口文件模块名称相同,这样抽离出来的新生成的framework模块会覆盖被抽离的framework模块
整合 webpack-dev-server
开发环境开启服务监听文件改动实时更新最新内容
$ npm install --save-dev webpack-dev-server
在build中添加webpack.dev.conf.js文件
const path = require('path'); const merge = require('webpack-merge'); const baseWebpackConfig = require('./webpack.base.conf.js'); const HtmlWebpackPlugin = require('html-webpack-plugin'); const webpack = require('webpack'); module.exports = merge(baseWebpackConfig, { mode: 'development', output: { filename: "js/[name].[hash:16].js", }, plugins: [ new HtmlWebpackPlugin({ template: 'public/index.html', inject: 'body', minify: { html5: true }, hash: false }), new webpack.HotModuleReplacementPlugin() ], devServer: { port: '8080', contentBase: path.join(__dirname, '../public'), compress: true, historyApiFallback: true, hot: true, https: false, noInfo: true, open: true, proxy: {} } });
在package.json scripts属性添加内容
"dev": "webpack-dev-server --inline --progress --config build/webpack.dev.conf.js",
npm run dev
自动打开浏览器打开入口页面实时更新
独立导出 css 文件
安装css相关依赖
sass less 预处理
$ npm install extract-text-webpack-plugin $ npm install style-loader css-loader postcss-loader autoprefixer --save-dev $ npm install less sass less-loader sass-loader stylus-loader node-sass --save-dev
webpack.base.conf.js 文件修改
// webpack.base.conf.js { test: /\.css$/, use: [ { loader: "style-loader" //在html中插入<style>标签 }, { loader: "css-loader",//获取引用资源,如@import,url() }, { loader: "postcss-loader", options: { plugins:[ require('autoprefixer')({ browsers:['last 5 version'] }) ] } } ] }, { test:/\.less$/, use: [ { loader: "style-loader" }, { loader: "css-loader" }, { loader: "postcss-loader",//自动加前缀 options: { plugins:[ require('autoprefixer')({ browsers:['last 5 version'] }) ] } }, { loader: "less-loader" } ] }, { test:/\.scss$/, use:[ { loader: "style-loader" }, { loader: "css-loader", }, { loader: "sass-loader" }, { loader: "postcss-loader", options: { plugins:[ require('autoprefixer')({ browsers:['last 5 version'] }) ] } } ] },
图片和路径处理
$ npm i file-loader url-loader --save-dev
webpack.base.conf.js 文件修改
// webpack.base.conf.js { test: /\.(png|jpg|gif|woff|svg|eot|woff2|tff)$/, use: 'url-loader?limit=8129', //注意后面那个limit的参数,当你图片大小小于这个限制的时候,会自动启用base64编码图片 exclude: /node_modules/ }
build 时报错
Error: Chunk.entrypoints: Use Chunks.groupsIterable and filter by instanceof Entrypoint instead
at Chunk.get (F:\react\createApp\node_modules\webpack\lib\Chunk.js:824:9)
webpack4.0中使用“extract-text-webpack-plugin”报错
解决办法
$ npm install extract-text-webpack-plugin@next
背景图片路径问题
由于css文件分离出来的原因,会导致在css文件夹下找images文件夹下的图片
解决办法 publicPath属性改为 '/',以绝对路径的方式寻找资源
{ test:/\.(png|jpg|gif)$/, use:[{ loader:'url-loader', options: { // outputPath:'../',//输出**文件夹 publicPath: '/', name: "images/[name].[ext]", limit:500 //是把小于500B的文件打成Base64的格式,写入JS } }] },
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