I'm using Webpack to bundle my main React JS code, and i recently started logging the size of this file using the Resources API.

I know that if the JS bundle has a size of 0 it means it was served from the browser cache, but why does the size change between my users? It could be 300kb, 546KB, 1.2MB and everything in between. Why is that? Shouldn't it be either its actual size (which is a single value) or 0 if it was served from cache?