When you write var moment = require('moment') in your code and pack with webpack, the size of the bundle file gets heavyweight because it includes all locale files.

To optimize the size, the two webpack plugins are available:

1. IgnorePlugin
2. ContextReplacementPlugin

You can remove all locale files with the IgnorePlugin.

const webpack = require('webpack'); module.exports = { //... plugins: [ // Ignore all locale files of moment.js new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/), ], };

And you can still load some locales in your code.

const moment = require('moment'); require('moment/locale/ja'); moment.locale('ja'); ...

Create React App and Next.js use this solution.

If you want to specify the including locale files in the webpack config file, you can use ContextReplacementPlugin.

const webpack = require('webpack'); module.exports = { //... plugins: [ // load `moment/locale/ja.js` and `moment/locale/it.js` new webpack.ContextReplacementPlugin(/moment[/\\]locale$/, /ja|it/), ], };

In this case, you don't need load the locale files in your code.

const moment = require('moment'); moment.locale('ja'); ...

• webpack: v3.10.0
• moment.js: v2.20.1

If you are looking for the alternatives to moment.js, please see https://github.com/you-dont-need/You-Dont-Need-Momentjs.

• http://stackoverflow.com/questions/25384360/how-to-prevent-moment-js-from-loading-locales-with-webpack/37172595
• moment/moment#2373