How to prevent moment.js from loading locales with webpack?

Question

Is there any way you can stop moment.js from loading all the locales (I just need English) when you're using webpack? I'm looking at the source and it seems that if hasModule is defined, which it is for webpack, then it always tries to require() every locale. I'm pretty sure this needs a pull request to fix. But is there any way we can fix this with the webpack config?

Here is my webpack config to load momentjs:

resolve: {
            alias: {
                moment: path.join(__dirname, "src/lib/bower/moment/moment.js")
            },
        },

Then anywhere I need it, I just do require('moment'). This works but it's adding about 250 kB of unneeded language files to my bundle. Also I'm using the bower version of momentjs and gulp.

Also if this can't be fixed by the webpack config here is a link to the function where it loads the locales. I tried adding && module.exports.loadLocales to the if statement but I guess webpack doesn't actually work in a way where that would work. It just requires no matter what. I think it uses a regex now so I don't really know how you would even go about fixing it.

Answer 1

The code require('./locale/' + name) can use every file in the locale dir. So webpack includes every file as module in your bundle. It cannot know which language you are using.

There are two plugins that are useful to give webpack more information about which module should be included in your bundle: ContextReplacementPlugin and IgnorePlugin.

require('./locale/' + name) is called a context (a require which contains an expression). webpack infers some information from this code fragment: A directory and a regular expression. Here: directory = ".../moment/locale" regular expression = /^.*$/. So by default every file in the locale directory is included.

The ContextReplacementPlugin allows to override the inferred information i.e. provide a new regular expression (to choose the languages you want to include).

Another approach is to ignore the require with the IgnorePlugin.

Here is an example:

var webpack = require("webpack");
module.exports = {
  // ...
  plugins: [
    new webpack.ContextReplacementPlugin(/moment[\/\\]locale$/, /de|fr|hu/)
    // new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/)
  ]
};