What are the point of webpack "runtime" files

Question

I am using webpack today for transpiling just my core business logic code, but are still using a CDN for all external libraries like jQuery, AngularJS, etc. I want to move these vendor libraries into webpack by using the SplitChunksPlugin, but when I followed an example I found here at SO I got the vendor bundle to get created, but at the same time it also created some extra files I am not sure about.

For every entry module I have declared in the webpack config, webpack not also creates a "runtime" version of these files"

For example I have a company.productA.core.bundle.js taht I have been using for a while but after adding the config for the split chunks I now also get a company.runtime~productA.core.bundle.js. Webpack has done the same for the other 8 modules I have being created.

I have tried searching for what these are but don't see anything about them on both the webpack documentation and SO.

Can someone explain to me what these files are meant for?

Answer 1

Each of the runtime files contains code that enables loading of your chunks. If you open any of those runtime files, you will see code that loads your chunks via Jsonp. Since you have asked webpack to split chunks, you are now free to load any chunk any time. Hence for each chunk, webpack emits these runtime files so that it can handle requires correctly.