webpack配置

webpack核心概念:

入口(entry) 指定webpack開始構(gòu)建的入口模塊本刽，從該模塊開始構(gòu)建并計(jì)算出直接或間接依賴的模塊或者庫
輸出(output)告訴webpack如何命名輸出的文件以及輸出的目錄
path ：入口文件最終要輸出到哪里母怜，
filename：輸出文件的名稱
publicPath：公共資源路徑
loader 由于webpack只能處理javascript戏挡，所以我們需要對一些非js文件處理成webpack能夠處理的模塊硕淑，比如sass文件
插件(plugins)
-chunkcoding split的產(chǎn)物彬坏，我們可以對一些代碼打包成一個單獨(dú)的chunk，比如某些公共模塊童太，去重米辐，更好的利用緩存∈槭停或者按需加載某些功能模塊翘贮，優(yōu)化加載時間。在webpack3及以前我們都利用CommonsChunkPlugin將一些公共代碼分割成一個chunk征冷，實(shí)現(xiàn)單獨(dú)加載择膝。在webpack4 中CommonsChunkPlugin被廢棄誓琼，使用SplitChunksPlugin

webpack安裝流程

step1:首先安裝Node.js
step2:通過全局先將webpack指令安裝進(jìn)電腦中npm install webpack -g npm install --save-dev webpack
step3:npm init(會生成一個package.json的文件)

step1: 創(chuàng)建項(xiàng)目文件夾, 例如webpack_test
step2: 在你的項(xiàng)目目錄下創(chuàng)建webpack.config.js配置文件, 通過這個文件進(jìn)行webpack的配置, 并且還要創(chuàng)建一些路徑保存基本文件,例如創(chuàng)建一個src文件夾检激，里面分別創(chuàng)建js,css,img文件夾
step3：在src的js下創(chuàng)建一個入口文件, 我創(chuàng)建的叫做entry.js, 在項(xiàng)目目錄再創(chuàng)建一個index.html用來調(diào)試使用. 編寫webpack.config.js文件,

//webpack.config.js
module.exports = {
    entry : './src/js/entry.js',//入口文件
    output : {//輸出文件
        filename : 'index.js',//輸出文件名
        path : __dirname + '/out'//輸出文件路徑
    },
}

index.html和入口文件entry.js

//index.html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8" />
    <title>ss</title>
</head>
<body>
111
    <script src="./out/index.js"></script>//注意在這里引入的是打包完成的js文件
</body>
</html>

//entry.js
console.log('1234');

webpack loader加載器

npm install babel-loader babel babel-core css-loader style-loader  url-loader file-loader less-loader less  --save-dev

修改webpack.config.js文件

module.exports = {
    entry :  './src/js/entry.js',
    output : {
        filename : 'index.js',
        path : __dirname + '/out'
    },
    module : {
        rules: [
            {test: /.js$/, use: ['babel-loader']},
            {test: /.css$/, use: ['style-loader', 'css-loader']},/*解析css, 并把css添加到html的style標(biāo)簽里*/
            //{test: /.css$/, use: ExtractTextPlugin.extract({fallback: 'style-loader',use: 'css-loader'})},/*解析css, 并把css變成文件通過link標(biāo)簽引入*/
            {test: /.(jpg|png|gif|svg)$/, use: ['url-loader?limit=8192&name=./[name].[ext]']},/*解析圖片*/
            {test: /.less$/, use: ['style-loader', 'css-loader', 'less-loader']}/*解析less, 把less解析成瀏覽器可以識別的css語言*/
        ]
    },
    }

webpack插件使用

修改webpack.config.js

var webpack = require('webpack');
var webpack = require('webpack');
var uglifyPlugin = new webpack.optimize.UglifyJsPlugin({minimize: true});//代碼壓縮

var CommonsChunkPlugin = new webpack.optimize.CommonsChunkPlugin('common');//把公共模塊提取出來, 并取名為'common'(名字自起), webpack之后再out文件夾下生成common.js, 測試時記得引入提取出來的公共模塊js文件

var ExtractTextPlugin = require("extract-text-webpack-plugin");//將css獨(dú)立引入變成link標(biāo)簽形式, 使用該插件需要獨(dú)立下載'npm install extract-text-webpack-plugin --save-dev', 同時下面的rules也必須更改

var providePlugin = new webpack.ProvidePlugin({$: 'jquery', jQuery: 'jquery', 'window.jQuery': 'jquery'});//引入jquery



module.exports = {
    entry : {index: './src/js/entry.js', index2: './src/js/entry2.js'},
    output : {
        filename : '[name].js',
        publicPath: __dirname + '/out',
        path : __dirname + '/out'
    },
    module : {
        rules: [
            {test: /.js$/, use: ['babel-loader']},
            //{test: /.css$/, use: ['style-loader', 'css-loader']},
            {test: /.css$/, use: ExtractTextPlugin.extract({fallback: 'style-loader',use: 'css-loader'})},
            {test: /.(jpg|png|gif|svg)$/, use: ['url-loader?limit=8192&name=./[name].[ext]']},
            {test: /.less$/, use: ['style-loader', 'css-loader', 'less-loader']}
        ]
    },
    plugins: [uglifyPlugin, CommonsChunkPlugin, new ExtractTextPlugin('[name].css'),providePlugin]//插件集合
}

webpack服務(wù)器

首先先定位目錄輸入命令 npm install webpack-dev-server -g, 修改webpack.config.js文件

publicPath: 'http://localhost:8080/out',

package.json

{
  "name": "pmall",
  "version": "4.2.6",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "dev": "cross-env NODE_ENV=development webpack-dev-server --open --port 4000 --hot --host 0.0.0.0 --content-base ./build --config ./build/webpack.config.dev.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "vue": "^2.5.3"
  },
  "devDependencies": {
    "babel-core": "^6.26.0",
    "babel-loader": "^7.1.2",
    "babel-plugin-transform-runtime": "^6.23.0",
    "babel-preset-es2015": "^6.24.1",
    "babel-preset-stage-0": "^6.24.1",
    "babel-preset-stage-2": "^6.24.1",
    "babel-runtime": "^6.26.0",
    "cross-env": "^5.1.1",
    "css-loader": "^0.28.7",
    "extract-text-webpack-plugin": "^3.0.2",
    "file-loader": "^1.1.5",
    "html-loader": "^0.5.1",
    "html-webpack-plugin": "^2.30.1",
    "node-sass": "^4.6.0",
    "postcss-loader": "^2.0.9",
    "sass-loader": "^6.0.6",
    "style-loader": "^0.19.0",
    "uglifyjs-webpack-plugin": "^1.0.1",
    "url-loader": "^0.6.2",
    "vue-loader": "^13.4.0",
    "vue-router": "^3.0.1",
    "vue-template-compiler": "^2.5.3",
    "webpack": "^3.8.1",
    "webpack-dev-server": "^2.9.4"
  },
  "description": ""
}