How to implement webpack2 project packaging optimization in vue-cli

Now I will share with you an article about vue-cli webpack2 project packaging optimization, which has a good reference value and I hope it will be helpful to everyone.

Reduce the file search scope

Configure resolve.modules

Webpack’s resolve.modules Configure the location of the module library (i.e. node_modules). When import 'vue' appears in js which is not a relative or absolute path, it will be found in the node_modules directory. However, the default configuration will be found through upward recursive search, but usually there is only one node_modules in the project directory, and it is in the project root directory. In order to reduce the search scope, you can directly specify the full path of node_modules; similarly, for aliases ( The same applies to the configuration of `alias):

function resolve (dir) {
 return path.join(__dirname, '..', dir)
}
module.exports = {
 resolve: {
 extensions: ['.js', '.vue', '.json'],
 modules: [
  resolve('src'),
  resolve('node_modules')
 ],
 alias: {
  'vue$': 'vue/dist/vue.common.js',
  'src': resolve('src'),
  'assets': resolve('src/assets'),
  'components': resolve('src/components'),
  // ...
  'store': resolve('src/store')
 }
 },
 ...
}

Reasonably set test & include & exclude

test: Conditions that must be met (regular expression, do not add quotes , match the files to be processed)

exclude: conditions that cannot be met (exclude directories that are not processed)

include: the path or file array that the imported file will be converted by the loader (to be processed directory included)

This can reduce unnecessary traversal, thereby reducing performance loss.

Replace the code compression tool

The UglifyJS plug-in provided by Webpack by default is slow due to the use of single-thread compression;

webpack-parallel-uglify- The plugin plugin can run the UglifyJS plugin in parallel, making more full and reasonable use of CPU resources, which can greatly reduce the build time;

Of course, this plugin should be used in the production environment rather than the development environment. After installing the plugin, proceed as follows Configuration:

// 删掉webpack提供的UglifyJS插件
// new webpack.optimize.UglifyJsPlugin({
// compress: {
//  warnings: false,
//  drop_console: true
// },
// sourceMap: true
// }),
// 增加 webpack-parallel-uglify-plugin来替换
const ParallelUglifyPlugin = require('webpack-parallel-uglify-plugin');
new ParallelUglifyPlugin({
 cacheDir: '.cache/', // 设置缓存路径，不改动的调用缓存，第二次及后面build时提速
 uglifyJS:{
 output: {
  comments: false
 },
 compress: {
  warnings: false
 }
 }
})

I also tried the same type of plug-in webpack-uglify-parallel, but it was not as effective as webpack-parallel-uglify-plugin (it may vary from project to project, you can use it in your project for comparison).

webpack-parallel-uglify-plugin The package produced by the plug-in is slightly larger than that of UglifyJsPlugin (but not obvious); compared with the increased size, I chose to pursue speed (after using it, it dropped from 40 seconds to 40 seconds). to 19 seconds).

Copy static files

Use the copy-webpack-plugin plug-in: copy the files in the specified folder to the specified directory; its configuration is as follows:

var CopyWebpackPlugin = require('copy-webpack-plugin')
plugins: [
 ...
 // copy custom static assets
 new CopyWebpackPlugin([
 {
  from: path.resolve(__dirname, '../static'),
  to: config.build.assetsSubDirectory,
  ignore: ['.*']
 }
 ])
]
DllPlugin & DllReferencePlugin

The concept of Dll should be borrowed from the dll of Windows system. A dll package is a purely dependent library. It cannot run on its own and is used to reference it in your app.

When packaging a dll, Webpack will make an index of all included libraries and write them in a manifest file, and the code that references the dll (dll user) only needs to read this manifest file when packaging. , that’s it.

1. Add the file webpack.dll.conf.js under the project build folder with the following content

var path = require('path')
var webpack = require('webpack')
module.exports = {
 entry: {
 vendor: [ // 这里填写需要的依赖库
  'babel-polyfill',
  'axios',
  'vue/dist/vue.common.js',
  'vue-router',
  'pingpp-js',
  "region-picker"
 ]
 },
 output: {
 path: path.resolve(__dirname, '../static/js'),
 filename: '[name].dll.js',
 library: '[name]_library'
 },
 module: {
 rules: [
  {
  test: /\.vue$/,
  loader: 'vue-loader'
  },
  {
  test: /\.js$/,
  loader: 'babel-loader',
  exclude: /node_modules/
  }
 ]
 },
 plugins: [
 new webpack.optimize.ModuleConcatenationPlugin(),
 new webpack.DllPlugin({
  path: path.join(__dirname, '.', '[name]-manifest.json'),
  libraryTarget: 'commonjs2',
  name: '[name]_library'
 }),
 new webpack.optimize.UglifyJsPlugin({
  compress: {
  warnings: false
  }
 })
 ]
}

2. Add the plugin part in the webpack.prod.conf.js file:

plugins: [
 ...
 // copy custom static assets
  new webpack.DllReferencePlugin({
    context: path.resolve(__dirname, '..'),
    manifest: require('./vendor-manifest.json')
  })
]

3. Add the following in the index.html file in the project root directory:

<body>
  <p id="app"></p>
  <!-- built files will be auto injected -->
  <script src="<%= webpackConfig.output.publicPath %>spa/js/vendor.dll.js"></script>   //添加这句，路径可根据所需修改
</body>

4. Add the command to package the dll in package.json

"build:dll": "webpack --config build/webpack.dll.conf.js"

5 , Command sequence

npm run build:dll //打包一次之后依赖库无变动不需要执行
npm run build

Advantages

Dll exists independently after being packaged, as long as the library it contains does not increase The hash will not change even if it is reduced or upgraded, so the online dll code does not need to be updated frequently with version releases.

After the App part code is modified, you only need to compile the app part code and the dll part. As long as the included libraries are not increased, decreased, or upgraded, there is no need to repackage. This also greatly improves the speed of each compilation.

Suppose you have multiple projects that use the same dependent libraries, they can share a dll.

19s->15s

Set babel's cacheDirectory to true

Modify babel-loader in webpack.base.conf.js:

loader: 'babel-loader?cacheDirectory=true',

15s->14s

Set noParse

If you are sure that there are no other new dependencies in a module, you can configure this, Webpack will no longer scan the dependencies in this file. This will improve performance for relatively large class libraries. For details, please see the following configuration:

module: {
 noParse: /node_modules\/(element-ui\.js)/,
 rules: [
  {
   ...
  }
}
happypack

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future. helpful.

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