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GeezerVison is showing github.com — Change 'keyof T' to always be string-like by ahejlsberg · Pull Request #12425 · microsoft/TypeScript

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@ahejlsberg

@ahejlsberg Anders Hejlsberg (ahejlsberg) commented Nov 21, 2016

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This PR revises keyof T to always be a subtype of string vs. a subtype of string | number. This more accurately reflects how properties work in JavaScript and allows us to use keyof T as the inferred type of a for...in variable when the object is of a type parameter type.

This change means that numeric index signatures are ignored by the keyof T operator and that it is never possible to use numbers as values for a keyof T.

Fixes #12314.

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Anders Hejlsberg (ahejlsberg) added 7 commits November 21, 2016 11:41
@ahejlsberg
Make keyof T a string-like type
76ceab9
@ahejlsberg
Update Record<K, T> type
854a20f
@ahejlsberg
Update tests
5498a95
@ahejlsberg
Accept new baselines
c555848
@ahejlsberg
Type of for-in variable is keyof T when object type is a type parameter
1710df5
@ahejlsberg
Accept new baselines
dbc661f
@ahejlsberg
Add test case
b662a8b
@msftclas Microsoft Contribution License Agreements (msftclas) added the cla-not-required label Nov 21, 2016
@ahejlsberg

Anders Hejlsberg (ahejlsberg) commented Nov 21, 2016

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Mohamed Hegazy (@mhegazy) Ping!
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mhegazy
Mohamed Hegazy (mhegazy) approved these changes Nov 21, 2016
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@ahejlsberg
Anders Hejlsberg (ahejlsberg) merged commit 77c0540 into master Nov 21, 2016
@ahejlsberg
Anders Hejlsberg (ahejlsberg) deleted the keyofOnlyStrings branch November 21, 2016 23:51
@mhegazy Mohamed Hegazy (mhegazy) mentioned this pull request Nov 22, 2016
Merge master into release-2.1 #12440
Merged
@ahejlsberg Anders Hejlsberg (ahejlsberg) mentioned this pull request Nov 24, 2016
Static types for dynamically named properties #11929
Merged
Ethan Resnick (ethanresnick) added a commit to ethanresnick/TypeScript that referenced this pull request Nov 27, 2016
@ethanresnick
Object.keys/entries: remove keyof & string intersections
29105a6 
Now that keyof T only returns string or string subtypes (microsoft#12425),
there’s no need to do keyof T & string.
@ethanresnick Ethan Resnick (ethanresnick) mentioned this pull request Nov 27, 2016
Object.keys() types refinement, and Object.entries() types bugfix #12253
Closed
Ethan Resnick (ethanresnick) added a commit to ethanresnick/TypeScript that referenced this pull request Nov 28, 2016
@ethanresnick
Update keyof tests to reflect microsoft#12425
8b7252c 
Removes number from all the keyof types, and adds a test that numeric
indexes are ignored.
@ethanresnick Ethan Resnick (ethanresnick) mentioned this pull request Nov 28, 2016
Update keyof tests to reflect #12425 #12533
Merged
Mohamed Hegazy (mhegazy) added a commit that referenced this pull request Nov 28, 2016
@mhegazy
Merge pull request #12533 from ethanresnick/keyof-tests
9cac35b 
Update keyof tests to reflect #12425
@mhegazy Mohamed Hegazy (mhegazy) mentioned this pull request Dec 19, 2016
Index signature parameter type should allow for enums #2491
Closed
@ChiriVulpes Chiri Vulpes (ChiriVulpes) mentioned this pull request Dec 20, 2016
Enums can not be used for index signature types #13042
Closed
@mhegazy Mohamed Hegazy (mhegazy) mentioned this pull request May 5, 2017
number should be subtype of keyof T[] #13715
Closed
@nevir Ian MacLeod (nevir) mentioned this pull request Jun 29, 2017
Unable to use numeric enums as keys of a map #16842
Closed
@yortus Troy Gerwien (yortus) mentioned this pull request Jan 15, 2018
Index which's key's type is number can accept string keys #21179
Closed
@kpdonn Kevin Donnelly (kpdonn) mentioned this pull request Mar 30, 2018
Consider adding symbolof type operator, like keyof but for unique symbol properties #20721
Closed
@microsoft Microsoft (microsoft) locked and limited conversation to collaborators Jun 19, 2018
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@mhegazy Mohamed Hegazy (mhegazy) mhegazy approved these changes
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3 participants

@ahejlsberg @mhegazy @msftclas
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