Array.groupByXxxx - clarify thisArg#14421
Merged
sideshowbarker merged 1 commit intomdn:mainfrom Mar 29, 2022
Merged
Conversation
Contributor
Preview URLs
FlawsNone! 🎉 External URLsURL: No new external URLs URL: No new external URLs |
sideshowbarker
approved these changes
Mar 29, 2022
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Array.groupBy() and Array.groupByToMap() take a
thisArgparameter.The docs followed the spec, which stated that the function is called with
undefinedif the argument is not specified. The engineering team clarified that this is is not the full story - functions are always called with a this argument, and the handling depends on the function and scope.Upshot is that if
thisArgwill actually only be undefined in a normal function called in strict mode. Otherwise it will take the scope appropriate for the function type - i.e. in an arrow function the lexical scope. In a normal function the calling scope.This follows on from discussion here: https://github.com/mdn/content/pull/13171/files#r816339510