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Updates from the 90th TC39 meeting

There were several items on the agenda, this post focuses on feature proposals and their progress from the meeting that was held between 6-9th June 2022.

Stage 4:

Array find from last: Proposal for .findLast() and .findLastIndex() methods on array and typed array.

Stage 3:

Symbols as WeakMap keys: Permit Symbols as keys in WeakMaps, entries in WeakSets and WeakRefs, and registered in FinalizationRegistries

Stage 2:

String.dedent: For multi-backtick templates with automatic margin stripping.

Duplicate named capture groups:Allow regex capturing group names to be repeated.

JSON.parse source text access: Extending JSON.parse to expose input source text.

Stage 1:

Faster Promise adoption: Reduce the number of microtask ticks required to adopt the state of a promise

RegExp Atomic Operators: Syntax to regular expressions to control backtracking in certain scenarios by treating certain portions of a pattern as "atomic", where backtracking information specific to that portion of the pattern is discarded when it matches successfully.

More updates:

Array#groupBy is renamed to Array#group, but why? Read on

Tried renaming it on Firefox:



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