一、环境搭建
1、安装
mkdir webpack-li && cd webpack-li
npm init -ynpm install --save-dev webpack webpack-dev-middleware webpack-dev-server webpack-manifest-plugin webpack-merge xml-loader clean-webpack-plugin css-loader csv-loader express file-loader html-webpack-plugin style-loader uglifyjs-webpack-plugin lodash2、添加文件夹src,在src下面添加文件much1.js
mkdir src
import _ from 'lodash';
function component() {
var element = document.createElement('div');
// Lodash（目前通过一个 script 脚本引入）对于执行这一行是必需的
element.innerHTML = _.join(['Hello111', 'webpack'], ' ');
element.classList.add('hello');
element.classList.add('el-icon-upload');
return element;
}
document.body.appendChild(component());
3、编辑webpack.config.js
const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const CleanWebpackPlugin = require('clean-webpack-plugin');
// var ManifestPlugin = require('webpack-manifest-plugin');
const webpack = require('webpack');
const UglifyJSPlugin = require('uglifyjs-webpack-plugin');
module.exports = {
entry: {
index: './src/much1.js'
},
output: {
filename: '[name].[chunkhash].js',
path: path.resolve(__dirname, 'dist')
},
// devtool: 'inline-source-map',//生成内页source map 文件
// devServer: {
// contentBase: './dist',
// hot: true
// },
module: {
rules: [{
test: /\.css$/,
use: [
'style-loader',
'css-loader'
]
}, {
test: /\.(png|svg|jpg|gif)$/,
use: [
'file-loader'
]
},
{
test: /\.(woff|woff2|eot|ttf|otf)$/,
use: [
'file-loader'
]
},
{
test: /\.(csv|tsv)$/,
use: [
'csv-loader'
]
},
{
test: /\.xml$/,
use: [
'xml-loader'
]
}
]
},
plugins: [
new CleanWebpackPlugin(['dist']),
// new ManifestPlugin(),//编译前后文件映射
// new UglifyJSPlugin(),//js压缩
new HtmlWebpackPlugin({
title: 'Output Management'
}),
// new webpack.optimize.CommonsChunkPlugin({
// name: 'common' // 指定公共 bundle 的名称。
// }),
// new webpack.NamedModulesPlugin(),
// new webpack.HotModuleReplacementPlugin()
],
};
4、编译—-1个文件，引入modules模块–lodash
webpack
二、测试过程
1、将webpack.config.js中的new webpack.optimize.CommonsChunkPlugin 代码放开，再次执行；生成的common.*.js中，主要包含文件关系window[“webpackJsonp”]，默认只是提炼webpack 的样板(boilerplate)
Hash: 901d6379c09764da9d03
Version: webpack 3.10.0
Time: 586ms
Asset Size Chunks Chunk Names
index.708570a5d9c1925e6cba.js 543 kB 0 [emitted] [big] index
common.d6716ad7b6bf34deabfe.js 5.82 kB 1 [emitted] common
index.html 285 bytes [emitted]
[0] ./src/much1.js 1.13 kB {0} [built]
[2] (webpack)/buildin/global.js 509 bytes {0} [built]
[3] (webpack)/buildin/module.js 517 bytes {0} [built]
+ 1 hidden module
Child html-webpack-plugin for "index.html":
1 asset
[2] (webpack)/buildin/global.js 509 bytes {0} [built]
[3] (webpack)/buildin/module.js 517 bytes {0} [built]
+ 2 hidden modules
2、增加much2.js文件
import _ from 'lodash';
console.log(
_.join(['Another', 'module', 'loaded!'], ' ')
);更改webpack.config.js
entry: {
much1: './src/much1.js',
much2: './src/much2.js'
},执行编译,生成的common.*.js中，包含文件关系window[“webpackJsonp”],以及 公共插件lodash–2个文件，引入modules模块–lodash
Hash: a33a11dba68a5a50d0c1
Version: webpack 3.10.0
Time: 698ms
Asset Size Chunks Chunk Names
much2.e93f8a1f67bb483eeb47.js 537 bytes 0 [emitted] much2
much1.b426830f89fd7baaf423.js 1.58 kB 1 [emitted] much1
common.8a1f8f7618e51d034b44.js 547 kB 2 [emitted] [big] common
index.html 361 bytes [emitted]
[1] ./src/much1.js 1.13 kB {1} [built]
[2] (webpack)/buildin/global.js 509 bytes {2} [built]
[3] (webpack)/buildin/module.js 517 bytes {2} [built]
[4] ./src/much2.js 88 bytes {0} [built]
+ 1 hidden module
Child html-webpack-plugin for "index.html":
1 asset
[2] (webpack)/buildin/global.js 509 bytes {0} [built]
[3] (webpack)/buildin/module.js 517 bytes {0} [built]
+ 2 hidden modules
3、修改much1.js的文件内容
element.innerHTML = _.join(['Hello', 'webpack'], ' ');执行编译，发现common.*.js 和 much1.*.js的版本号发生改变
Hash: 017f08627b69bf79219d
Version: webpack 3.10.0
Time: 655ms
Asset Size Chunks Chunk Names
much2.e93f8a1f67bb483eeb47.js 537 bytes 0 [emitted] much2
much1.f16da266b64d94bdfd24.js 1.58 kB 1 [emitted] much1
common.d2f18d59fa51e749bf16.js 547 kB 2 [emitted] [big] common
index.html 361 bytes [emitted]
[1] ./src/much1.js 1.13 kB {1} [built]
[2] (webpack)/buildin/global.js 509 bytes {2} [built]
[3] (webpack)/buildin/module.js 517 bytes {2} [built]
[4] ./src/much2.js 88 bytes {0} [built]
+ 1 hidden module
Child html-webpack-plugin for "index.html":
1 asset
[2] (webpack)/buildin/global.js 509 bytes {0} [built]
[3] (webpack)/buildin/module.js 517 bytes {0} [built]
+ 2 hidden modules
4、增加math.js
export function square(x) {
return x * x;
}
export function cube(x) {
return x * x * x;
}更改much1.js
import _ from 'lodash';
import { cube } from './math.js';
function component() {
var element = document.createElement('div');
// Lodash（目前通过一个 script 脚本引入）对于执行这一行是必需的
element.innerHTML = _.join(['Hello', 'webpack'], ' ');
element.classList.add('hello');
element.classList.add('el-icon-upload');
var element = document.createElement('pre');
element.innerHTML = [
'Hello webpack!',
'5 cubed is equal to ' + cube(5)
].join('\n\n');
return element;
}
document.body.appendChild(component());编译执行–2个文件，其中一个引入第3个js, math.js被编译在much1.*.js
5、在上一步的基础上，修改much2.js
import _ from 'lodash';
import { cube } from './math.js';
console.log(
_.join(['Another', 'module', 'loaded!'], ' ')
);编译执行–2个文件，都引入第3个js,math.js被编译在common.*.js,默认只是提炼webpack 的样板(boilerplate)，以及被2个及以上文件引用过的js
6、修改webpack.config.js
new webpack.optimize.CommonsChunkPlugin({
name: 'vendor',
minChunks: function (module, count) {
// any required modules inside node_modules are extracted to vendor
return (
module.resource &&
/\.js$/.test(module.resource) &&
module.resource.indexOf(
path.join(__dirname, './node_modules')
) === 0
)
}
}),
再次编译，生成的common.*.js中，只包含文件关系window[“webpackJsonp”] 和 lodash,只有node_modules中的模块被打包进common.*.js
7、修改webpack.config.js,再增加
new webpack.optimize.CommonsChunkPlugin({
name: 'manifest',
chunks: ['common']
}),编译执行，生成的common.*.js中，只包含文件关系window[“webpackJsonp”] ，common.*.js中包含 lodash
Hash: e89c001c2ded3524d449
Version: webpack 3.10.0
Time: 1441ms
Asset Size Chunks Chunk Names
common.6b94cc3a187b7be511ae.js 541 kB 0 [emitted] [big] common
much2.2d5b108f2c7292042637.js 914 bytes 1 [emitted] much2
much1.e5fff3acc8b12de04f6e.js 1.96 kB 2 [emitted] much1
manifest.e0257ac8e9e9948ace74.js 5.88 kB 3 [emitted] manifest
index.html 440 bytes [emitted]
[0] ./src/math.js 94 bytes {1} {2} [built]
[2] ./src/much1.js 1.11 kB {2} [built]
[3] (webpack)/buildin/global.js 509 bytes {0} [built]
[4] (webpack)/buildin/module.js 517 bytes {0} [built]
[5] ./src/much2.js 122 bytes {1} [built]
+ 1 hidden module
Child html-webpack-plugin for "index.html":
1 asset
[2] (webpack)/buildin/global.js 509 bytes {0} [built]
[3] (webpack)/buildin/module.js 517 bytes {0} [built]
+ 2 hidden modules
8、修改much1.js
element.innerHTML = _.join(['Hello33333', 'webpack'], ' ');编译执行，只有much1.*.js 和 manifest.*.js 的版本号发送变化
Hash: 62d9c993ba573fda02fc
Version: webpack 3.10.0
Time: 705ms
Asset Size Chunks Chunk Names
common.6b94cc3a187b7be511ae.js 541 kB 0 [emitted] [big] common
much2.2d5b108f2c7292042637.js 914 bytes 1 [emitted] much2
much1.33e3d1b003899654d18d.js 1.97 kB 2 [emitted] much1
manifest.cec9b6b2718268e923f3.js 5.88 kB 3 [emitted] manifest
index.html 440 bytes [emitted]
[0] ./src/math.js 94 bytes {1} {2} [built]
[2] ./src/much1.js 1.11 kB {2} [built]
[3] (webpack)/buildin/global.js 509 bytes {0} [built]
[4] (webpack)/buildin/module.js 517 bytes {0} [built]
[5] ./src/much2.js 122 bytes {1} [built]
+ 1 hidden module
Child html-webpack-plugin for "index.html":
1 asset
[2] (webpack)/buildin/global.js 509 bytes {0} [built]
[3] (webpack)/buildin/module.js 517 bytes {0} [built]
+ 2 hidden modules
三、测试分析
1、webpack.optimize.CommonsChunkPlugin 默认提炼代码：webpack打包逻辑，在两个及以上页面出现过引入的js
2、vue-cli打包，使用了两次CommonsChunkPlugin——
new webpack.optimize.CommonsChunkPlugin({
name: 'vendor',
minChunks: function (module, count) {
// any required modules inside node_modules are extracted to vendor
return (
module.resource &&
/\.js$/.test(module.resource) &&
module.resource.indexOf(
path.join(__dirname, '../node_modules')
) === 0
)
}
}),
// extract webpack runtime and module manifest to its own file in order to
// prevent vendor hash from being updated whenever app bundle is updated
new webpack.optimize.CommonsChunkPlugin({
name: 'manifest',
chunks: ['vendor']
})
第一次，将从node_modules引入的js文件打包到verdor.js；第二次，从第一步的verdor.js文件中抽离出webpack打包逻辑,形成manifest.js
效果：优化页面性能。第一次打包的verdor.js变化几率较小，可以长久的存储在浏览器缓存中；第二次分离出来的逻辑manifest.js变化几率大，更新时重新加载js耗用的流量少，提升页面打开性能
劣势：如果是多页面系统，verdor.js包含大量的公用js，某些可能是其他页面不需要使用的
