Add support for the insert option

[giuseppeg]

This PR contains a:

New feature.

Motivation / Use-Case

This new option mirrors the behavior of style-loader which allows users to pass a custom insert function that takes care of inserting chunks. This is particularly useful when the initiator is in the parent window but the application renders inside of an iframe.

Breaking Changes

None. This change is backwards compatible: when this option is not provided the plugin will keep inserting link tags as before i.e. to the document's head.

Additional Info

I found a similar PR #371 but the proposed API forces the user to return an element that the plugin will use as insertion point.

[jsf-clabot]

All committers have signed the CLA.

[alexander-akait]

Thanks for work, need add tests

[giuseppeg]

@evilebottnawi thank you for taking a look. Can you be a bit more specific as for what kind of extra tests we need to merge this PR? I have added some already but I wasn't quite sure if those were enough or the right way to test this feature.

[alexander-akait]

We need test case, here examples https://github.com/webpack-contrib/mini-css-extract-plugin/tree/master/test/cases, just add test for string and Function

[giuseppeg]

Should I just create a new folder in cases? If so I thought that those kind of tests are not end to end and don't test runtime (eg. insert a link tag on a page) - please correct me if I am wrong.

[alexander-akait]

Should I just create a new folder in cases?

yes, insert-string and insert-function

If so I thought that those kind of tests are not end to end and don't test runtime (eg. insert a link tag on a page)

Let's implement this, it is not difficult

[yisar]

Is there any progress here? It's not very difficult, but it's urgent.

[giuseppeg]

@132yse I might have time to work on this sometime next week. If you need it earlier please go ahead and take over it, you'd just need to add tests.

[codecov]

Codecov Report

Merging #459 into master will increase coverage by 0.15%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #459      +/-   ##
==========================================
+ Coverage   88.65%   88.81%   +0.15%     
==========================================
  Files           5        5              
  Lines         423      429       +6     
  Branches       92       97       +5     
==========================================
+ Hits          375      381       +6     
  Misses         46       46              
  Partials        2        2              

Impacted Files	Coverage Δ
src/loader.js	89.01% <ø> (ø)
src/index.js	88.58% <100.00%> (+0.32%)	⬆️

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[giuseppeg]

@evilebottnawi it seems that webpack is not emitting this file and it 404s. Also I am not sure jsdom supports getComputedStyle. In that case I think we either get rid of this test or need to set up something like Puppeteer which IMO is out of scope.

[ankurbigcomm]

@giuseppeg @evilebottnawi Any Update here?! We might need this for one of our use cases. Any possibility this is getting merged soon?

[giuseppeg]

I think @ScriptedAlchemy took over this but his PR is blocked.

[ScriptedAlchemy]

Merge my PR into your branch if needed. I’m not blocked just ran out of time to perform the last requests. Started working on module Federation and that’s a monster that has taken all my capacity

[ScriptedAlchemy]

If you need it now. Extract css has us it for months. https://github.com/faceyspacey/extract-css-chunks-webpack-plugin

[alexander-akait]

#609 improved

[ScriptedAlchemy]

Yaaaay