skimi / test-webpack-sideeffects

Two chunks chunk1.js and chunk2.js.

Each importing a function of lodash using the package index.js

(this only works with es modules!)

import { join } from 'lodash-es';

import { last } from 'lodash-es';

Before the option sideEffects existed we would expect the complete content of lodash-es to be imported as a single module and not split in the different chunk. So the recommendation was import join from 'lodash-es/join'; to import each module separately.

That's the result of npm run build-sideEffect and /dist-side-effect.

Now with sideEffects option on the chunk1 will contain join and chunk2 last. All other functions will be tree-shaked successfully.

That's the result of npm run build and /dist.