feat: add iterator methods to esnext

tsc/internal/bundled/libs/lib.esnext.d.ts

@@ -25,3 +25,4 @@ and limitations under the License.
 /// <reference lib="esnext.typedarrays" />
 /// <reference lib="esnext.temporal" />
 /// <reference lib="esnext.date" />
+/// <reference lib="esnext.iterator" />

tsc/internal/bundled/libs/lib.esnext.iterator.d.ts

@@ -0,0 +1,119 @@
+/*! *****************************************************************************
+Copyright (c) Microsoft Corporation. All rights reserved.
+Licensed under the Apache License, Version 2.0 (the "License"); you may not use
+this file except in compliance with the License. You may obtain a copy of the
+License at http://www.apache.org/licenses/LICENSE-2.0
+
+THIS CODE IS PROVIDED ON AN *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
+WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
+MERCHANTABILITY OR NON-INFRINGEMENT.
+
+See the Apache Version 2.0 License for specific language governing permissions
+and limitations under the License.
+***************************************************************************** */
+
+
+/// <reference lib="es2025.iterator" />
+
+export {};
+
+interface IteratorZipShortestOptions {
+    /**
+     * Stops when any input is exhausted.
+     */
+    mode?: "shortest";
+}
+
+interface IteratorZipLongestOptions<T> {
+    /**
+     * Continues until every input is exhausted.
+     */
+    mode: "longest";
+
+    /**
+     * Values used when an input is exhausted before the others.
+     */
+    padding?: T;
+}
+
+interface IteratorZipStrictOptions {
+    /**
+     * Requires every input to yield the same number of values.
+     * If not, a `TypeError` will be thrown when an input is exhausted before others.
+     */
+    mode: "strict";
+}
+
+type IteratorZipOptions<T> =
+    | IteratorZipShortestOptions
+    | IteratorZipLongestOptions<T>
+    | IteratorZipStrictOptions;
+
+type IteratorInput<T> = Iterable<T> | Iterator<T>;
+
+type IteratorInputTuple = readonly [] | readonly [IteratorInput<unknown>, ...IteratorInput<unknown>[]];
+
+type IteratorYield<T> = T extends IteratorInput<infer U> ? U : never;
+
+type IteratorZipResult<T, TExtra = never> = {
+    -readonly [K in keyof T]: IteratorYield<T[K]> | TExtra;
+};
+
+declare global {
+    interface IteratorObject<T, TReturn, TNext> {
+        /**
+         * Creates an iterator whose values are arrays containing successive values from this iterator.
+         * @param chunkSize The maximum number of values in each array.
+         */
+        chunks(chunkSize: number): IteratorObject<T[], undefined, unknown>;
+
+        /**
+         * Creates a string by concatenating the values of this iterator, separated by the specified separator.
+         * `null` and `undefined` values contribute an empty string.
+         * @param separator A string used to separate values. If omitted, a comma is used.
+         */
+        join(separator?: string): string;
+
+        /**
+         * Determines whether this iterator yields the specified value using SameValueZero comparison.
+         * @param searchElement The value to locate.
+         * @param skippedElements The number of values to skip before searching.
+         */
+        includes(searchElement: T, skippedElements?: number): boolean;
+    }
+
+    interface IteratorConstructor {
+        /**
+         * Creates an iterator whose values are arrays containing values yielded at the same position by each input iterator or iterable.
+         * @param iterables An iterable of iterators or iterables to zip.
+         * @param options Controls how differing input lengths are handled.
+         */
+        zip(iterables: readonly [], options?: IteratorZipOptions<Iterable<unknown>>): IteratorObject<never, undefined, unknown>;
+
+        /**
+         * Creates an iterator whose values are arrays containing values yielded at the same position by each input iterator or iterable.
+         * @param iterables An iterable of iterators or iterables to zip.
+         * @param options Controls how differing input lengths are handled.
+         */
+        zip<T extends IteratorInputTuple>(iterables: T, options: IteratorZipLongestOptions<NoInfer<IteratorZipResult<T>>> & { padding: NoInfer<IteratorZipResult<T>>; }): IteratorObject<IteratorZipResult<T>, undefined, unknown>;
+        zip<T extends readonly IteratorInput<unknown>[] | []>(iterables: T, options?: IteratorZipShortestOptions | IteratorZipStrictOptions): IteratorObject<IteratorZipResult<T>, undefined, unknown>;
+        zip<T extends readonly IteratorInput<unknown>[] | []>(iterables: T, options: IteratorZipOptions<NoInfer<Partial<IteratorZipResult<T>>>>): IteratorObject<IteratorZipResult<T, undefined>, undefined, unknown>;
+
+        /**
+         * Creates an iterator whose values are arrays containing values yielded at the same position by each input iterator or iterable.
+         * @param iterables An iterable of iterators or iterables to zip.
+         * @param options Controls how differing input lengths are handled.
+         */
+        zip<T extends IteratorInput<unknown>>(iterables: Iterable<T>, options?: IteratorZipShortestOptions | IteratorZipStrictOptions): IteratorObject<IteratorYield<T>[], undefined, unknown>;
+        zip<T extends IteratorInput<unknown>>(iterables: Iterable<T>, options: IteratorZipOptions<NoInfer<Iterable<IteratorYield<T>>>>): IteratorObject<(IteratorYield<T> | undefined)[], undefined, unknown>;
+
+        /**
+         * Creates an iterator whose values are objects containing values yielded at the same position by each iterator or iterable in the input object.
+         * @param iterables An object whose enumerable own properties contain iterators or iterables to zip.
+         * @param options Controls how differing input lengths are handled.
+         */
+        zipKeyed<T extends object>(iterables: T & Record<keyof T, IteratorInput<unknown>>, options?: IteratorZipShortestOptions | (IteratorZipLongestOptions<NoInfer<IteratorZipResult<T>>> & { padding: NoInfer<IteratorZipResult<T>>; }) | IteratorZipStrictOptions): IteratorObject<IteratorZipResult<T>, undefined, unknown>;
+        zipKeyed<T extends object>(iterables: T & Record<keyof T, IteratorInput<unknown>>, options: IteratorZipOptions<NoInfer<Partial<IteratorZipResult<T>>>>): IteratorObject<IteratorZipResult<T, undefined>, undefined, unknown>;
+    }
+}

tsc/internal/compiler/program_test.go

@@ -111,6 +111,7 @@ var esnextLibs = []string{
 	"lib.es2025.iterator.d.ts",
 	"lib.es2025.promise.d.ts",
 	"lib.es2025.regexp.d.ts",
+	"lib.esnext.iterator.d.ts",
 	"lib.esnext.array.d.ts",
 	"lib.esnext.collection.d.ts",
 	"lib.esnext.date.d.ts",

tsc/internal/tsoptions/enummaps.go

@@ -106,9 +106,9 @@ var LibMap = collections.NewOrderedMapFromList([]collections.MapEntry[string, an
 	{Key: "esnext.regexp", Value: "lib.es2024.regexp.d.ts"},
 	{Key: "esnext.string", Value: "lib.es2024.string.d.ts"},
 	{Key: "esnext.float16", Value: "lib.es2025.float16.d.ts"},
-	{Key: "esnext.iterator", Value: "lib.es2025.iterator.d.ts"},
 	{Key: "esnext.promise", Value: "lib.es2025.promise.d.ts"},
 	// ESNext By-feature options
+	{Key: "esnext.iterator", Value: "lib.esnext.iterator.d.ts"},
 	{Key: "esnext.array", Value: "lib.esnext.array.d.ts"},
 	{Key: "esnext.collection", Value: "lib.esnext.collection.d.ts"},
 	{Key: "esnext.date", Value: "lib.esnext.date.d.ts"},

tsc/testdata/baselines/reference/compiler/builtinIterator.symbols

@@ -184,7 +184,7 @@ const iter1 = Iterator.from(g1);
 
 declare const iter2: IteratorObject<string>;
 >iter2 : Symbol(iter2, Decl(builtinIterator.ts, 71, 13))
->IteratorObject : Symbol(IteratorObject, Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.esnext.disposable.d.ts, --, --), Decl(lib.es2025.iterator.d.ts, --, --))
+>IteratorObject : Symbol(IteratorObject, Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.esnext.disposable.d.ts, --, --), Decl(lib.es2025.iterator.d.ts, --, --), Decl(lib.esnext.iterator.d.ts, --, --))
 
 const iter3 = iter2.flatMap(() => g1);
 >iter3 : Symbol(iter3, Decl(builtinIterator.ts, 72, 5))

tsc/testdata/baselines/reference/compiler/builtinIterator.types

@@ -4,9 +4,9 @@
 const iterator = Iterator.from([0, 1, 2]);
 >iterator : IteratorObject<number, undefined, unknown>
 >Iterator.from([0, 1, 2]) : IteratorObject<number, undefined, unknown>
->Iterator.from : <T>(value: Iterator<T, unknown, undefined> | Iterable<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
+>Iterator.from : <T>(value: Iterable<T, unknown, undefined> | Iterator<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
 >Iterator : IteratorConstructor
->from : <T>(value: Iterator<T, unknown, undefined> | Iterable<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
+>from : <T>(value: Iterable<T, unknown, undefined> | Iterator<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
 >[0, 1, 2] : number[]
 >0 : 0
 >1 : 1
@@ -52,9 +52,9 @@ const zero = iterator.filter(isZero);
 const iteratorFromBare = Iterator.from({
 >iteratorFromBare : IteratorObject<string, undefined, unknown>
 >Iterator.from({  next() {    return {      done: Math.random() < .5,      value: "a string",    };  },}) : IteratorObject<string, undefined, unknown>
->Iterator.from : <T>(value: Iterator<T, unknown, undefined> | Iterable<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
+>Iterator.from : <T>(value: Iterable<T, unknown, undefined> | Iterator<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
 >Iterator : IteratorConstructor
->from : <T>(value: Iterator<T, unknown, undefined> | Iterable<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
+>from : <T>(value: Iterable<T, unknown, undefined> | Iterator<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
 >{  next() {    return {      done: Math.random() < .5,      value: "a string",    };  },} : { next(): { done: boolean; value: string; }; }
 
   next() {
@@ -244,9 +244,9 @@ declare const g1: Generator<string, number, boolean>;
 const iter1 = Iterator.from(g1);
 >iter1 : IteratorObject<string, undefined, unknown>
 >Iterator.from(g1) : IteratorObject<string, undefined, unknown>
->Iterator.from : <T>(value: Iterator<T, unknown, undefined> | Iterable<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
+>Iterator.from : <T>(value: Iterable<T, unknown, undefined> | Iterator<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
 >Iterator : IteratorConstructor
->from : <T>(value: Iterator<T, unknown, undefined> | Iterable<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
+>from : <T>(value: Iterable<T, unknown, undefined> | Iterator<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
 >g1 : Generator<string, number, boolean>
 
 declare const iter2: IteratorObject<string>;

tsc/testdata/baselines/reference/compiler/iteratorChunks.errors.txt

@@ -0,0 +1,10 @@
+iteratorChunks.ts(3,33): error TS2345: Argument of type 'string' is not assignable to parameter of type 'number'.
+
+
+==== iteratorChunks.ts (1 errors) ====
+    const chunks: number[][] = Iterator.from([1, 2, 3]).chunks(2).toArray();
+
+    Iterator.from([1, 2, 3]).chunks("2");
+                                    ~~~
+!!! error TS2345: Argument of type 'string' is not assignable to parameter of type 'number'.
+

tsc/testdata/baselines/reference/compiler/iteratorChunks.js

@@ -0,0 +1,12 @@
+//// [tests/cases/compiler/iteratorChunks.ts] ////
+
+//// [iteratorChunks.ts]
+const chunks: number[][] = Iterator.from([1, 2, 3]).chunks(2).toArray();
+
+Iterator.from([1, 2, 3]).chunks("2");
+
+
+//// [iteratorChunks.js]
+"use strict";
+const chunks = Iterator.from([1, 2, 3]).chunks(2).toArray();
+Iterator.from([1, 2, 3]).chunks("2");

tsc/testdata/baselines/reference/compiler/iteratorChunks.symbols

@@ -0,0 +1,20 @@
+//// [tests/cases/compiler/iteratorChunks.ts] ////
+
+=== iteratorChunks.ts ===
+const chunks: number[][] = Iterator.from([1, 2, 3]).chunks(2).toArray();
+>chunks : Symbol(chunks, Decl(iteratorChunks.ts, 0, 5))
+>Iterator.from([1, 2, 3]).chunks(2).toArray : Symbol(IteratorObject.toArray, Decl(lib.es2025.iterator.d.ts, --, --))
+>Iterator.from([1, 2, 3]).chunks : Symbol(IteratorObject.chunks, Decl(lib.esnext.iterator.d.ts, --, --))
+>Iterator.from : Symbol(IteratorConstructor.from, Decl(lib.es2025.iterator.d.ts, --, --))
+>Iterator : Symbol(Iterator, Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2025.iterator.d.ts, --, --))
+>from : Symbol(IteratorConstructor.from, Decl(lib.es2025.iterator.d.ts, --, --))
+>chunks : Symbol(IteratorObject.chunks, Decl(lib.esnext.iterator.d.ts, --, --))
+>toArray : Symbol(IteratorObject.toArray, Decl(lib.es2025.iterator.d.ts, --, --))
+
+Iterator.from([1, 2, 3]).chunks("2");
+>Iterator.from([1, 2, 3]).chunks : Symbol(IteratorObject.chunks, Decl(lib.esnext.iterator.d.ts, --, --))
+>Iterator.from : Symbol(IteratorConstructor.from, Decl(lib.es2025.iterator.d.ts, --, --))
+>Iterator : Symbol(Iterator, Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2025.iterator.d.ts, --, --))
+>from : Symbol(IteratorConstructor.from, Decl(lib.es2025.iterator.d.ts, --, --))
+>chunks : Symbol(IteratorObject.chunks, Decl(lib.esnext.iterator.d.ts, --, --))
+

tsc/testdata/baselines/reference/compiler/iteratorChunks.types

@@ -0,0 +1,35 @@
+//// [tests/cases/compiler/iteratorChunks.ts] ////
+
+=== iteratorChunks.ts ===
+const chunks: number[][] = Iterator.from([1, 2, 3]).chunks(2).toArray();
+>chunks : number[][]
+>Iterator.from([1, 2, 3]).chunks(2).toArray() : number[][]
+>Iterator.from([1, 2, 3]).chunks(2).toArray : () => number[][]
+>Iterator.from([1, 2, 3]).chunks(2) : IteratorObject<number[], undefined, unknown>
+>Iterator.from([1, 2, 3]).chunks : (chunkSize: number) => IteratorObject<number[], undefined, unknown>
+>Iterator.from([1, 2, 3]) : IteratorObject<number, undefined, unknown>
+>Iterator.from : <T>(value: Iterable<T, unknown, undefined> | Iterator<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
+>Iterator : IteratorConstructor
+>from : <T>(value: Iterable<T, unknown, undefined> | Iterator<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
+>[1, 2, 3] : number[]
+>1 : 1
+>2 : 2
+>3 : 3
+>chunks : (chunkSize: number) => IteratorObject<number[], undefined, unknown>
+>2 : 2
+>toArray : () => number[][]
+
+Iterator.from([1, 2, 3]).chunks("2");
+>Iterator.from([1, 2, 3]).chunks("2") : IteratorObject<number[], undefined, unknown>
+>Iterator.from([1, 2, 3]).chunks : (chunkSize: number) => IteratorObject<number[], undefined, unknown>
+>Iterator.from([1, 2, 3]) : IteratorObject<number, undefined, unknown>
+>Iterator.from : <T>(value: Iterable<T, unknown, undefined> | Iterator<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
+>Iterator : IteratorConstructor
+>from : <T>(value: Iterable<T, unknown, undefined> | Iterator<T, unknown, undefined>) => IteratorObject<T, undefined, unknown>
+>[1, 2, 3] : number[]
+>1 : 1
+>2 : 2
+>3 : 3
+>chunks : (chunkSize: number) => IteratorObject<number[], undefined, unknown>
+>"2" : "2"
+

tsc/testdata/baselines/reference/compiler/iteratorIncludes.errors.txt

@@ -0,0 +1,16 @@
+iteratorIncludes.ts(4,35): error TS2345: Argument of type 'string' is not assignable to parameter of type 'number'.
+iteratorIncludes.ts(6,38): error TS2345: Argument of type 'string' is not assignable to parameter of type 'number'.
+
+
+==== iteratorIncludes.ts (2 errors) ====
+    const includes: boolean = Iterator.from([1, 2, 3]).includes(2);
+    const includesAfterSkipping: boolean = Iterator.from([1, 2, 3]).includes(2, 1);
+
+    Iterator.from([1, 2, 3]).includes("1");
+                                      ~~~
+!!! error TS2345: Argument of type 'string' is not assignable to parameter of type 'number'.
+
+    Iterator.from([1, 2, 3]).includes(2, "1");
+                                         ~~~
+!!! error TS2345: Argument of type 'string' is not assignable to parameter of type 'number'.
+

tsc/testdata/baselines/reference/compiler/iteratorIncludes.js

@@ -0,0 +1,17 @@
+//// [tests/cases/compiler/iteratorIncludes.ts] ////
+
+//// [iteratorIncludes.ts]
+const includes: boolean = Iterator.from([1, 2, 3]).includes(2);
+const includesAfterSkipping: boolean = Iterator.from([1, 2, 3]).includes(2, 1);
+
+Iterator.from([1, 2, 3]).includes("1");
+
+Iterator.from([1, 2, 3]).includes(2, "1");
+
+
+//// [iteratorIncludes.js]
+"use strict";
+const includes = Iterator.from([1, 2, 3]).includes(2);
+const includesAfterSkipping = Iterator.from([1, 2, 3]).includes(2, 1);
+Iterator.from([1, 2, 3]).includes("1");
+Iterator.from([1, 2, 3]).includes(2, "1");