Webpack 4 “size exceeds the recommended limit (244

问题:

I have two files which are combined under 600 bytes (.6kb) as below.

So how is it that my app.bundle.js is so large (987kb) and more importantly how does one manage the size of it?

src file index.js

import _ from 'lodash';
import printMe from './print.js';


  function component() {
    var element = document.createElement('div');
    var btn = document.createElement('button');

    // Lodash, now imported by this script
    element.innerHTML = _.join(['Hello', 'webpack'], ' ');

    btn.innerHTML = 'click and check console';
    btn.onclick = printMe;

    element.appendChild(btn);

    return element;
  }

  document.body.appendChild(component());

src file print.js

export default function printMe() {
  consoe.log('Called from print.js');
}

webpack.config.js

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

module.exports = {
  entry: {
    app: './src/index.js',
    print:'./src/print.js'
  },
  devtool: 'inline-source-map',
  plugins: [
    new CleanWebpackPlugin(['dist']),
    new HtmlWebpackPlugin({
        title: 'Output Management'
    })
  ],
  output: {
    filename: '[name].bundle.js',
    path: path.resolve(__dirname, 'dist')
  }
};

package.json

{
  "name": "my-webpack-4-proj",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "mode": "development",
  "scripts": {
    "dev": "webpack --mode development",
    "build": "webpack --mode production",
    "watch": "webpack --watch",
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "clean-webpack-plugin": "^0.1.19",
    "css-loader": "^0.28.11",
    "csv-loader": "^2.1.1",
    "file-loader": "^1.1.11",
    "html-webpack-plugin": "^3.0.6",
    "style-loader": "^0.20.3",
    "webpack": "^4.1.1",
    "webpack-cli": "^2.0.12",
    "xml-loader": "^1.2.1"
  },
  "dependencies": {
    "express": "^4.16.3",
    "lowdash": "^1.2.0"
  }
}

Warning message:

WARNING in asset size limit: The following asset(s) exceed the recommended size limit (244 KiB). This can impact web performance. Assets: app.bundle.js (964 KiB)

回答1:

This happens because webpack is bundling all your code dependencies. And as you are using lodash, so lodash minified version will be added to your source code. Plus you are including the source maps:

devtool: 'inline-source-map',

While this should be fine for debug, there is no reason to include your source maps in a Prod build. So some things that you can do to reduce your bundle size.

1. Make sure to set properly the mode: flag inside your webpack config. You can put either mode: 'development', or mode: 'production'. This will hint webpack about what kind of build you are doing so it will give you the proper warnings.
2. Make sure to not include source maps on your prod build
3. Avoid overusing external dependencies that you don't need and make.

Sometimes even these things will not bring your bundle size to below 244kb, what you can do in these cases is to split your bundle and start to use logical chunks. First of all, you can easily separate your js from your styesheets by using the extract text plugin.

Another technique that you can use are dynamic imports.

Dynamic Imports: Split code via inline function calls within modules

This will allow you to break your code logically into modules tied to the screens so only the required libraries will be loaded. For more info about dynamic imports, you can check the official documentation. https://webpack.js.org/guides/code-splitting/

回答2:

I had the same problem. My bundle file was (1.15 MiB). In my webpack.config.js, replacing :

devtool: 'inline-source-map'

by this line:

devtool: false,

takes my bundle file size from 1.15 MiB to 275 Kib.

Or create 2 separate webpack config files. One for dev and one for prod. In the prod webpack config file, delete the devtool option.

回答3:

Simply use below code in webpack.config.js :

 performance: {
    hints: false,
    maxEntrypointSize: 512000,
    maxAssetSize: 512000
}

or follow

You can create multiple config file for (development, production). In dev config file use devtool or others necessary dev configuration and vice versa .

you have to use webpack-merge package and config package.json scripts code like

"scripts": {
 "test": "echo \"Error: no test specified\" && exit 1",
 "start": "webpack --open --config webpack.dev.js",
 "dev": "webpack-dev-server --mode development --open",
 "build": "webpack --config webpack.prod.js"
 },

For example :

create a file webpack.common.js

// webpack.common.js

  use your common configuration like entry, output, module, plugins,

Create webpack.dev.js

// webpack.dev.js
const merge = require('webpack-merge');
const common = require('./webpack.common.js');

module.exports = merge(common, {
mode: 'development',
devtool: 'inline-source-map',
devServer: {
    contentBase: './dist'
 }
});

Create webpack.prod.js

const merge = require('webpack-merge');
const common = require('./webpack.common.js');

module.exports = merge(common, {
    mode: 'production',
    performance: {
        hints: false,
        maxEntrypointSize: 512000,
        maxAssetSize: 512000
    }
});

回答4:

set mode flag to development/production in webpack.config.js. Example-

var mode = process.env.NODE_ENV || 'development';
module.exports = {
    ...
    devtool: (mode === 'development') ? 'inline-source-map' : false,
    mode: mode,
    ...
}