improvement(server): Allow setting async/defer via extraProps

[jackyef]

Summary

Solving #337

Default: async: true, defer: false

Scenarios:

• extractor.getScriptTags({ defer: true }) will return <script async defer ...></script> (because async is true by default)
• extractor.getScriptTags({ async: true }) will return <script async ...></script>
• extractor.getScriptTags({ async: false, defer: true }) will return <script defer ...></script>
• extractor.getScriptTags() will return <script async ...></script> to keep the default behaviour, preventing breaking change.

Using both async and defer together might have a valid use case as explained here

Test plan

Tests are added to ChunkExtractor.test.js

[gregberge]

• async should be true by default
• The micro-optimization reduces the code lisibility (and probably does not change anything)
• The method getRequiredChunksScriptTag should support async and defer like others, the difference of options should be coded in getScriptTags and getScriptElements.
• Documentation is missing

[jackyef]

The method getRequiredChunksScriptTag should support async and defer like other

One question about this though, does async/defer have impact when the script is inline? (Which is the case of getRequiredChunksScriptTag) @gregberge

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[jackyef]

@gregberge Hi, are we really deciding on this as wontfix?

[ArgonAlex]

Just want to express my desire for this functionality. Right now I'm resorting to hackily string replacing async with defer.

[suhanw]

Would love this feature too

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[theKashey]

Stalebot go away

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[qingzhou729]

Would love this feature too！！

[qingzhou729]

Would love this feature too！！