webpack学习-10天搞定webpack4

时间 2019-11-18

标签 webpack 学习 10天搞定 webpack4 繁體版

原文原文链接

第12天课程-多页:多入口，匹配多个打包的jscss

const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = {
    mode: 'development',
    entry: {
        home: './src/home.js',
        other: './src/other.js'
    },
    output: {
        filename: '[name].js',
        path: path.resolve(__dirname, 'dist')
    },
    plugins: [
        new HtmlWebpackPlugin({
            template: './src/home.html',
            filename: 'home.html',
            chunks:['home']
        }),
        new HtmlWebpackPlugin({
            template: './src/other.html',
            filename: 'other.html',
            chunks:['other']
        })
    ]
}

补充章节:webpack-modehtml

mode分为development/production,默认为production。每一个选项的默认配置以下(common指两个配置项都存在的属性):前端

common:vue

//parent chunk中解决了的chunk会被删除
optimization.removeAvailableModules:true
//删除空的chunks
optimization.removeEmptyChunks:true
//合并重复的chunk
optimization.mergeDuplicateChunks:true

production node

//性能相关配置
performance:{hints:"error"....}
//某些chunk的子chunk已一种方式被肯定和标记,这些子chunks在加载更大的块时没必要加载
optimization.flagIncludedChunks:true
//给常常使用的ids更短的值
optimization.occurrenceOrder:true
//肯定每一个模块下被使用的导出
optimization.usedExports:true
//识别package.json or rules sideEffects 标志
optimization.sideEffects:true
//尝试查找模块图中能够安全链接到单个模块中的段。- -
optimization.concatenateModules:true
//使用uglify-js压缩代码
optimization.minimize:true

developmentreact

//调试
devtool:eval
//缓存模块, 避免在未更改时重建它们。
cache:true
//缓存已解决的依赖项, 避免从新解析它们。
module.unsafeCache:true
//在 bundle 中引入「所包含模块信息」的相关注释
output.pathinfo:true
//在可能的状况下肯定每一个模块的导出,被用于其余优化或代码生成。
optimization.providedExports:true
//找到chunk中共享的模块,取出来生成单独的chunk
optimization.splitChunks:true
//为 webpack 运行时代码建立单独的chunk
optimization.runtimeChunk:true
//编译错误时不写入到输出
optimization.noEmitOnErrors:true
//给模块有意义的名称代替ids
optimization.namedModules:true
//给模chunk有意义的名称代替ids
optimization.namedChunks:true

webpack运行时还会根据mode设置一个全局变量process.env.NODE_ENV,jquery

这里的process.env.NODE_ENV不是node中的环境变量,而是webpack.DefinePlugin中定义的全局变量,容许你根据不一样的环境执行不一样的代码.webpack

生产环境下,uglify打包代码时会自动删除不可达代码,也就是说生产环境压缩后最终的代码为:es6

第13天课程-配置source-mapweb

安装依赖

npm install -D babel-loader @babel/core @babel/preset-env 

npm install webpack-dev-server --save-dev


devtool设置项理解，eval 能够理解为发射，不是编译阶段产生

  //devtool: 'source-map',//产生文件，能够显示行和列
  //devtool: 'eval-source-map',//不实际产生文件，可是能够显示行和列
  //devtool: 'cheap-module-source-map',//不显示列，产生文件
  devtool: 'cheap-module-eval-source-map',//不显示列，不产生文件

试验代码src/home.js:

class Demo{
    constructor(){
        console.loga();
    }
}
let d=new Demo();

const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = {
  mode: 'production',
  entry: {
    home: './src/home.js',
  },
  output: {
    filename: 'index.js',
    path: path.resolve(__dirname, 'dist')
  }, 
  //devtool: 'source-map',//产生文件，能够显示行和列
  //devtool: 'eval-source-map',//不实际产生文件，可是能够显示行和列
  //devtool: 'cheap-module-source-map',//不显示列，产生文件
  devtool: 'cheap-module-eval-source-map',//不显示列，不产生文件
  module: {
    rules: [
      {
        test: /\.m?js$/,
        exclude: /(node_modules|bower_components)/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env']
          }
        }
      }
    ]
  },
  plugins: [
    new HtmlWebpackPlugin({
      template: './src/home.html',
      filename: 'index.html',
      chunks: ['home']
    })
  ]
}

14章节:watch用法,执行npm run build时候开始

更改完代码以后，当即build,产生编译文件，

"start": "webpack-dev-server",不会产生文件，因此用watch

const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = {
  mode: 'production',
  entry: {
    home: './src/home.js',
  },
  output: {
    filename: 'index.js',
    path: path.resolve(__dirname, 'dist')
  }, 
  watch:true,
  watchOptions:{
    poll:1000,//每秒检查一次变更
    aggregateTimeout:500,//防抖延迟，500秒以后输入，
    ignored: /node_modules/ //ignored: "files/**/*.js"
  },
  module: {
    rules: [
      {
        test: /\.m?js$/,
        exclude: /(node_modules|bower_components)/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env']
          }
        }
      }
    ]
  },
  plugins: [
    new HtmlWebpackPlugin({
      template: './src/home.html',
      filename: 'index.html',
      chunks: ['home']
    })
  ]
}

15：webpack小插件介绍

cleanWebpackPlugin:npm install clean-webpack-plugin -D

关键代码:

const { CleanWebpackPlugin } = require('clean-webpack-plugin'); // 引入清除文件插件
new CleanWebpackPlugin()

官方说明:详细说明

        /**
         * All files inside webpack's output.path directory will be removed once, but the
         * directory itself will not be. If using webpack 4+'s default configuration,
         * everything under <PROJECT_DIR>/dist/ will be removed.
         * Use cleanOnceBeforeBuildPatterns to override this behavior.
         *
         * During rebuilds, all webpack assets that are not used anymore
         * will be removed automatically.
         *
         * See `Options and Defaults` for information
         */
全部output.path目录都会被一次删除，目录自己不会删除

copyWebPackPlugin:

const CopyWebpackPlugin = require('copy-webpack-plugin'); // 文件拷贝
new CopyWebpackPlugin([{from:'./doc',to:'./'}])

bannerPlugin:

let webpack=require('webpack');
new webpack.BannerPlugin('版权全部,违反必究 2019 copyright')

本章节webpack配置文件

const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const { CleanWebpackPlugin } = require('clean-webpack-plugin'); // 引入清除文件插件
const CopyWebpackPlugin  = require('copy-webpack-plugin'); // 引入清除文件插件
let webpack=require('webpack');

module.exports = {
  mode: 'development',
  entry: {
    home: './src/home.js',
  },
  output: {
    filename: 'index.js',
    path: path.resolve(__dirname, 'dist')
  }, 
  module: {
    rules: [
      {
        test: /\.m?js$/,
        exclude: /(node_modules|bower_components)/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env']
          }
        }
      }
    ]
  },
  plugins: [
    new HtmlWebpackPlugin({
      template: './src/home.html',
      filename: 'index.html',
      chunks: ['home']
    }),
    new CleanWebpackPlugin(),
    new CopyWebpackPlugin([{from:'./doc',to:'./'}]),
    new webpack.BannerPlugin('版权全部,违反必究 2019 copyright')
  ]
}

16章节:webpack跨域问题

webpack端口默认是8080 若是请求这么写，会跨域，跨域是浏览器自己的限制，若是使用浏览器跨域设置，能够请求到数据

1：devServer-proxy设置

本地express服务器:localhost:3000/api/user

代理设置:proxy:{'/api':'http://localhost:3000'}

可是不是服务端每一个接口都是api开头的，因此须要用下面的方式

本地express服务器:localhost:3000/user

代理devServer设置

proxy:{

'/api':{

target:'http://localhost:3000',

pathRewrite:{'/api':''}

}

2：单纯模拟数据mock 启动钩子函数

3：有服务端，可是不想用代理处理,用express 启动webpack 端口用express端口

npm install webpack-dev-middleware --save-dev   //安装依赖

server.js

let express = require('express');
let config=require('./webpack.config');
const webpack = require('webpack');
const middleware = require('webpack-dev-middleware');
const compiler = webpack(config);
let app = express();
app.use(
  middleware(compiler, {
  })
);
app.get('/api/user', (req, res) => {
    res.json({ "name": "珠峰设计-express" });
})
app.listen(3000);

webpack.config.js

const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const { CleanWebpackPlugin } = require('clean-webpack-plugin'); // 引入清除文件插件
const CopyWebpackPlugin = require('copy-webpack-plugin'); // 引入清除文件插件
let webpack = require('webpack');

module.exports = {
  mode: 'development',
  entry: {
    home: './src/home.js',
  },
  devServer: {
    contentBase: path.join(__dirname, 'dist'),
    compress: true,
    before(app) {
      console.log(app);
      app.get('/before', (req, res) => {
        res.json({ "name": "我试mock数据-before" });
      })
    },
    port: 9000,
    /*proxy:{
      '/api':'http://localhost:3000'
    } */
    proxy: {
      '/api': {
        target: 'http://localhost:3000',
        pathRewrite: { '/api': '' }//须要先启动3000端口的服务
      }
    }
  },

  output: {
    filename: 'index.js',
    path: path.resolve(__dirname, 'dist')
  },
  module: {
    rules: [
      {
        test: /\.m?js$/,
        exclude: /(node_modules|bower_components)/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env']
          }
        }
      }
    ]
  },
  plugins: [
    new HtmlWebpackPlugin({
      template: './src/home.html',
      filename: 'index.html',
      chunks: ['home']
    }),
    new CleanWebpackPlugin(),
    new CopyWebpackPlugin([{ from: './doc', to: './' }]),
    new webpack.BannerPlugin('版权全部,违反必究 2019 copyright')
  ]
}

17:resolve属性的配置,解析的意思,文件查找别名后缀等配置

Webpack 在启动后会从配置的入口模块出发找出全部依赖的模块，Resolve 配置 Webpack 如何寻找模块所对应的文件。 Webpack 内置 JavaScript 模块化语法解析功能，默认会采用模块化标准里约定好的规则去寻找，但你也能够根据本身的须要修改默认的规则

安装后模块:就是会在node_modules里面Bin里面有，不须要"/"

模块目录指定：

别名:引入bootstrap样式为例

alias:名称比较长，可是文件名称比较长，想取一个短的名字

mainFields 可是能不能先找style 再找js mainFields:['style','main'] 字段名称为bootstrap里面package.json key

extensions: 后缀扩展

默认:extensions: ['.js', '.json']当访问aa 先找aa.js 再找aa.json若是找不到，报错

若是须要typescript须要改为extensions: ['.ts', '.js', '.json']

须要css的话，把css加进去

mainFiles:文件名，暂时没有使用场景

18：定义环境变量

把环境变量注入代码里面,插件:new webpack.

    new webpack.DefinePlugin({
     'DEV':"'dev'",
     'DevTest':JSON.stringify('devTest'),
     'DevBoolean':true,
     'DevBooleanWithSingle':'true',
     'EXPRESSIONWITHNOTDOT':'1+1',
     'EXPRESSIONWITHDOT':JSON.stringify('1+1'),
    }),

输出结果:

19;区分不一样环境变量

webpack.config.js分开生产和开发环境，

webpack.base.js :公共的

webpack.dev.js 开发的

webpack.prod.js 生产的

安装插件npm install webpack-merge -D

webpack.dev.js文件内容，这样咱们就能够把配置给分开

const { smart } = require('webpack-merge'); const base = require('./webpack.base.js'); module.exports = smart(base, {'mode':'development'})

20:优化设置

新建一个空的工程并安装插件

npm init -y
npm install webpack webpack-cli html-web
pack-plugin @babel/core babel-loader @babel/preset-env @babel/preset-react jquery -D

>webpack配置里面的noParse:不解析依赖项

src-index.js文件

import jquery from 'jquery';

这样反复编译几回发现，编译时间是缩短了，我电脑表现大概节约200ms时间

>IgnorePlugin插件:忽略某些模块，不打包进来

webpack配置里面exclude include排除目录(node_modules),包含src

安装moment 时间处理库：npm insall moment -D

安装开发服务器:npm install webpack-dev-server

webpack.config.js文件

const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const webpack=require('webpack');

module.exports = {
    entry: './src/index.js',
    output: {
        filename: 'bundle.js',
        path: path.resolve(__dirname, 'dist'),
    },
    module: {
        rules: [
            {
                test: /\.m?js$/,
                exclude: /(node_modules|bower_components)/,
                include:path.resolve("src"),
                use: {
                    loader: 'babel-loader',
                    options: {
                        presets: ['@babel/preset-env', '@babel/preset-react']
                    }
                }
            }
        ]
    },
    plugins: [
        new HtmlWebpackPlugin({
            template: './public/index.html',
        }),
        new webpack.IgnorePlugin(/\.\/locale/,/moment/)

    ],
};

index.js

import jquery from 'jquery';
import moment from 'moment';
import 'moment/locale/zh-cn';
moment.locale('zh-cn');//这一句不引入也正确
let r=moment().endOf('day').fromNow();
console.log(r);

>dllPlugin插件:减小打包体积

安装npm install react react-dom

>happypack多线程打包js,css打包中间插入一层happypack

>webpack自带的一些优化,避免没必要要的tree-shaking,做用域提高scope hosting

生产环境去除没有用的代码，开发环境有的，tree-shaking

只有import 管用，require不能够,es6模块会把结果放到default对象上

前端推荐import

webpack会省略一些能够简化的代码

25:webpack抽取公共代码 optimization-splitChunks-cacheGroups里面配置，多入口文件

webpack配置文件

optimization:{
splitChunks:{
cacheGroups:{
common:{
chunks:'initial',//抽离阶段
minSize:0,抽离大小
minChunks:2//引用多少次就开始抽离

},
vendor:{
priority:1, //避免直接走第一步，不走第二步
test:/node_modules/,
chunks:'initial',
minSize:0,
minChunks；2

}





}
}
}

26：懒加载功能webpack

意义:安装插件@babel/plugin-syntax-dynamic-import

vue react的路由懒加载实现

button的点击事件里面代码

import('./source.js');

options:{
    presets:['@babel/preset-env','@babel/preset-react'],
    plugins:['@babel/plugin-syntax-dynamic-import ']
}

27：webpack热更新开发环境用默认强制更新，从新编译

devserver:hot:true

两个插件:webpack.NamedModulesPlugin /webpack.HotModuleReplacementPlugin

index.js

import s from './a.js';
if (module.hot) {
    module.hot.accept('./a.js', (s) => {
        let a=import('./a');//
        a.then(function(response){
            console.log(response);
        });
        let b=require('./a.js');
        console.log(b);

    })

}

const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const webpack=require('webpack');

module.exports = {
    entry: './src/index.js',
    output: {
        filename: 'bundle.js',
        path: path.resolve(__dirname, 'dist'),
    },
    devServer:{
     port:3000,
     open:true,
     hot:true,
     contentBase:'./dist'
    },
    module: {
        rules: [
            {
                test: /\.m?js$/,
                exclude: /(node_modules|bower_components)/,
                include:path.resolve("src"),
                use: {
                    loader: 'babel-loader',
                    options: {
                        presets: ['@babel/preset-env', '@babel/preset-react']
                    }
                }
            }
        ]
    },
    plugins: [
        new HtmlWebpackPlugin({
            template: './public/index.html',
        }),
        new webpack.IgnorePlugin(/\.\/locale/,/moment/),
        new webpack.NamedModulesPlugin(),
        new webpack.HotModuleReplacementPlugin()

    ],
};

28-33:webpack-tapable 同步钩子和异步钩子

webpack 本质事件流，主要依赖于发布订阅模式