VueJS - 构建后 dist 中的多个 js 文件

Question

当我运行 "npm run build" 时，我得到的不是单个 build.js 文件，而是 4 或 5 个 javascript 文件。这些 javascript 文件的大小约为 1MB。为什么会这样？

文件夹结构如下

build.js

// https://github.com/shelljs/shelljs
require('./check-versions')()
require('shelljs/global')
env.NODE_ENV = 'production'

var path = require('path')
var config = require('../config')
var ora = require('ora')
var webpack = require('webpack')
var webpackConfig = require('./webpack.prod.conf')

console.log(
  '  Tip:\n' +
  '  Built files are meant to be served over an HTTP server.\n' +
  '  Opening index.html over file:// won\'t work.\n'
)

var spinner = ora('building for production...')
spinner.start()

var assetsPath = path.join(config.build.assetsRoot, config.build.assetsSubDirectory)
rm('-rf', assetsPath)
mkdir('-p', assetsPath)
cp('-R', 'static/*', assetsPath)

webpack(webpackConfig, function (err, stats) {
  spinner.stop()
  if (err) throw err
  process.stdout.write(stats.toString({
    colors: true,
    modules: false,
    children: false,
    chunks: false,
    chunkModules: false
  }) + '\n')
})

webpack.prod.conf.js

var path = require('path')
var config = require('../config')
var utils = require('./utils')
var webpack = require('webpack')
var merge = require('webpack-merge')
var baseWebpackConfig = require('./webpack.base.conf')
var ExtractTextPlugin = require('extract-text-webpack-plugin')
var HtmlWebpackPlugin = require('html-webpack-plugin')
var env = config.build.env

var webpackConfig = merge(baseWebpackConfig, {
  module: {
    loaders: utils.styleLoaders({ sourceMap: config.build.productionSourceMap, extract: true })
  },
  devtool: config.build.productionSourceMap ? '#source-map' : false,
  output: {
    path: config.build.assetsRoot,
    filename: utils.assetsPath('js/[name].[chunkhash].js'),
    chunkFilename: utils.assetsPath('js/[id].[chunkhash].js')
  },
  vue: {
    loaders: utils.cssLoaders({
      sourceMap: config.build.productionSourceMap,
      extract: true
    })
  },
  plugins: [
    // http://vuejs.github.io/vue-loader/en/workflow/production.html
    new webpack.DefinePlugin({
      'process.env': env
    }),
    new webpack.optimize.UglifyJsPlugin({
      compress: {
        warnings: true
      }
    }),
    new webpack.optimize.OccurrenceOrderPlugin(),
    // extract css into its own file
    new ExtractTextPlugin(utils.assetsPath('css/[name].[contenthash].css')),
    // generate dist index.html with correct asset hash for caching.
    // you can customize output by editing /index.html
    // see https://github.com/ampedandwired/html-webpack-plugin
    new HtmlWebpackPlugin({
      filename: config.build.index,
      template: 'index.html',
      inject: true,
      minify: {
        removeComments: true,
        collapseWhitespace: true,
        removeAttributeQuotes: true
        // more options:
        // https://github.com/kangax/html-minifier#options-quick-reference
      },
      // necessary to consistently work with multiple chunks via CommonsChunkPlugin
      chunksSortMode: 'dependency'
    }),
    // split vendor js into its own file
    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']
    })
  ]
})

if (config.build.productionGzip) {
  var CompressionWebpackPlugin = require('compression-webpack-plugin')

  webpackConfig.plugins.push(
    new CompressionWebpackPlugin({
      asset: '[path].gz[query]',
      algorithm: 'gzip',
      test: new RegExp(
        '\.(' +
        config.build.productionGzipExtensions.join('|') +
        ')$'
      ),
      threshold: 10240,
      minRatio: 0.8
    })
  )
}

module.exports = webpackConfig

Answer 1

所有这些都存在，因为您的配置文件说它们应该存在。

manifest.js 存在是因为配置围绕：

// extract webpack runtime and module manifest to its own file in order to
// prevent vendor hash from being updated whenever app bundle is updated

vendor.js 存在是因为配置：

// split vendor js into its own file

和 .map 文件 source maps 用于调试：

sourceMap: config.build.productionSourceMap

Answer 2

如前一条评论所述，您之所以获得它们，是因为 vue-cli 中的默认 webpack 配置已设置为执行此操作。通常 app.js 包含所有自定义代码，包括 .vue 文件和主要 javascript 文件。 venodr.js file on the other way 如果我没记错的话，从 node_modules 收集你所有的导入并将它们放在这个文件中。

例如，如果您 import vueRouter from 'vue-router' 它会将 vue-router javascript 放入 vendor.js 文件中，因为它被用作 npm 的插件。由于您不会经常在生产中更改插件，因此将它们放在单独的文件中非常有用，因为它们会被缓存。一旦您在应用程序中更新并部署它，用户将下载更新的 app.js，其中包含您为应用程序编写的代码，而不是再次下载所有内容（插件 + 您的应用程序）。

将插件放在单独的 js 包中是许多 frameworks/setups 中常用的做法。（例如 .NET MVC 包）

Answer 3

您的 .map 文件是源地图。

A source map is a file that maps from the transformed source to the original source, enabling the browser to reconstruct the original source and present the reconstructed original in the debugger.
» Source

您在生产中不一定需要它们，因为它们会使应用程序变得更大，而且您无论如何也不应该在那里进行调试。

您可以通过设置 productionSourceMap: false 来关闭它们。检查您的 config\index.js 文件并查找此部分：

module.exports = {
  build: {
    env: require('./prod.env'),
    productionSourceMap: false
    ....

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