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add support of fromEntries #26149

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1 change: 1 addition & 0 deletions src/compiler/commandLineParser.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,7 @@ namespace ts {
["es2018.promise", "lib.es2018.promise.d.ts"],
["es2018.regexp", "lib.es2018.regexp.d.ts"],
["esnext.array", "lib.esnext.array.d.ts"],
["esnext.object", "lib.esnext.object.d.ts"],
["esnext.symbol", "lib.esnext.symbol.d.ts"],
["esnext.asynciterable", "lib.esnext.asynciterable.d.ts"],
["esnext.intl", "lib.esnext.intl.d.ts"]
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1 change: 1 addition & 0 deletions src/lib/esnext.d.ts
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@@ -1,5 +1,6 @@
/// <reference lib="es2018" />
/// <reference lib="esnext.asynciterable" />
/// <reference lib="esnext.array" />
/// <reference lib="esnext.object" />
/// <reference lib="esnext.symbol" />
/// <reference lib="esnext.intl" />
13 changes: 13 additions & 0 deletions src/lib/esnext.object.d.ts
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@@ -0,0 +1,13 @@
interface ObjectConstructor {
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@RyanCavanaugh the new file will need to be added to the setup of the VS SDK. you will need to run VS\scripts\distributeLibFiles.bat to update the setup.

/**
* Returns an object from an array of properties key/values
* @param entries Array that contains the properties key and value.
*/
fromEntries<T>(entries: ArrayLike<[string, T]> | Iterable<[string, T]>): Record<string, T>;
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Would be nice to support tuple types but not sure the compiler is clever enough to deal with that without having to define 200 overloads

fromEntries<K1 extends string, V1>(entries: [[K1, V1]]): { [K1]: V1 }
fromEntries<K1 extends string, V1, K2 extends string, V2>(entries: [[K1, V1], [K2, V2]]): { [K1]: V1; [K2]: V2 }
// ...

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It was nice if typescript had any way to declare types mapping from tuple to object

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Is there a real use case for Object.fromEntries with a fixed number of entries? Seems like almost always you can just use object literal syntax in a case like that.

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I have a use case for that :)
im doing a-lot of these manipulations.
and if i had a generic way to express it, that would be awesome

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@Bnaya can you share a realistic code snippet where object literal syntax doesn't work but fixed-length fromEntries does?

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Drive-by comment: fromEntries allows Symbol keys, not just strings.

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image

😸

The more comprehensive version is:

  1. The first argument must be an Iterable. The algorithm literally calls @@iterator. Can't get away with ArrayLikes here.
  2. The iterable must yield an object of the shape { 0?: string | number | symbol | null | { valueOf(): string | number } | { toString(): string }; 1?: any }. This is probably not very useful for the actual type definition, and is incomplete as the valueOf may just be any other coercible value; but the point is that the Iterable's value needs not be an array or ArrayLike.
    2a) The "0" key / first element of tuple just needs to be something that can be cast into an object key, and that includes undefined. undefined becomes "undefined" and null becomes "null". Pretty much the only thing I found that "doesn't work" is Object.create(null).
    2b) The "1" key / second element of tuple is the value associated with the key.
    2c) Any of those keys may be getters or just missing entirely. They may even be write-only setters.
  3. Duplicates overwrite each other in iteration order. The last value wins.

Current TypeScript treats tuples as assignable to objects with numeric literal keys. Using <K extends keyof any, T> as the generic argument and Iterable<{ 0: K, 1: T }> should work for most cases; with maybe a few more overloads for index signatures and a catch-all for mixed tuples.


/**
* Returns an object from an array of properties key/values
* @param entries Array that contains the properties key and value.
*/
fromEntries(entries: ArrayLike<[string, any]> | Iterable<[string, any]>): Record<string, any>;
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@saschanaz saschanaz Feb 7, 2019 •
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tc39/ecma262#1274

fromEntries only accepts iterable object so probably we should remove ArrayLike here. The Firefox implementation also throws for array-like object.

(Edit: Or replace it with ReadonlyArray if we want it to be ES5 compatible.)

}
1 change: 1 addition & 0 deletions src/lib/libs.json
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@
"es2018.intl",
"esnext.asynciterable",
"esnext.array",
"esnext.object",
"esnext.symbol",
"esnext.intl",
// Default libraries
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6 changes: 3 additions & 3 deletions src/testRunner/unittests/commandLineParsing.ts
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Expand Up @@ -57,7 +57,7 @@ namespace ts {
assertParseResult(["--lib", "es5,invalidOption", "0.ts"],
{
errors: [{
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.object', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
category: Diagnostics.Argument_for_0_option_must_be_Colon_1.category,
code: Diagnostics.Argument_for_0_option_must_be_Colon_1.code,
file: undefined,
Expand Down Expand Up @@ -259,7 +259,7 @@ namespace ts {
assertParseResult(["--lib", "es5,", "es7", "0.ts"],
{
errors: [{
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.object', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
category: Diagnostics.Argument_for_0_option_must_be_Colon_1.category,
code: Diagnostics.Argument_for_0_option_must_be_Colon_1.code,
file: undefined,
Expand All @@ -278,7 +278,7 @@ namespace ts {
assertParseResult(["--lib", "es5, ", "es7", "0.ts"],
{
errors: [{
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.object', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
category: Diagnostics.Argument_for_0_option_must_be_Colon_1.category,
code: Diagnostics.Argument_for_0_option_must_be_Colon_1.code,
file: undefined,
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8 changes: 4 additions & 4 deletions src/testRunner/unittests/convertCompilerOptionsFromJson.ts
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Expand Up @@ -263,7 +263,7 @@ namespace ts {
file: undefined,
start: 0,
length: 0,
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.object', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
code: Diagnostics.Argument_for_0_option_must_be_Colon_1.code,
category: Diagnostics.Argument_for_0_option_must_be_Colon_1.category
}]
Expand Down Expand Up @@ -294,7 +294,7 @@ namespace ts {
file: undefined,
start: 0,
length: 0,
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.object', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
code: Diagnostics.Argument_for_0_option_must_be_Colon_1.code,
category: Diagnostics.Argument_for_0_option_must_be_Colon_1.category
}]
Expand Down Expand Up @@ -325,7 +325,7 @@ namespace ts {
file: undefined,
start: 0,
length: 0,
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.object', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
code: Diagnostics.Argument_for_0_option_must_be_Colon_1.code,
category: Diagnostics.Argument_for_0_option_must_be_Colon_1.category
}]
Expand Down Expand Up @@ -356,7 +356,7 @@ namespace ts {
file: undefined,
start: 0,
length: 0,
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
messageText: "Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'esnext', 'dom', 'dom.iterable', 'webworker', 'webworker.importscripts', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'esnext.array', 'esnext.object', 'esnext.symbol', 'esnext.asynciterable', 'esnext.intl'.",
code: Diagnostics.Argument_for_0_option_must_be_Colon_1.code,
category: Diagnostics.Argument_for_0_option_must_be_Colon_1.category
}]
Expand Down