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// Copyright 2018-2026 the Deno authors. MIT license.
// This module is browser compatible.
/** Order option for {@linkcode SortByOptions}. */
export type Order = "asc" | "desc";
/** Options for {@linkcode sortBy}. */
export type SortByOptions = {
/**
* The order to sort the elements in.
*
* @default {"asc"}
*/
order: Order;
};
/**
* Returns all elements in the given collection, sorted by their result using
* the given selector. The selector function is called only once for each
* element. Ascending or descending order can be specified through the `order`
* option. By default, the elements are sorted in ascending order.
*
* @typeParam T The type of the iterator elements.
* @typeParam U The type of the selected values.
*
* @param iterator The iterator to sort.
* @param selector The selector function to get the value to sort by. The
* function receives the element and its index.
* @param options The options for sorting.
*
* @returns A new array containing all elements sorted by the selector.
*
* @example Usage with numbers
* ```ts
* import { sortBy } from "@std/collections/sort-by";
* import { assertEquals } from "@std/assert";
*
* const people = [
* { name: "Anna", age: 34 },
* { name: "Kim", age: 42 },
* { name: "John", age: 23 },
* ];
* const sortedByAge = sortBy(people, (person) => person.age);
*
* assertEquals(sortedByAge, [
* { name: "John", age: 23 },
* { name: "Anna", age: 34 },
* { name: "Kim", age: 42 },
* ]);
*
* const sortedByAgeDesc = sortBy(people, (person) => person.age, { order: "desc" });
*
* assertEquals(sortedByAgeDesc, [
* { name: "Kim", age: 42 },
* { name: "Anna", age: 34 },
* { name: "John", age: 23 },
* ]);
* ```
*
* @example Usage with strings
* ```ts
* import { sortBy } from "@std/collections/sort-by";
* import { assertEquals } from "@std/assert";
*
* const people = [
* { name: "Anna" },
* { name: "Kim" },
* { name: "John" },
* ];
* const sortedByName = sortBy(people, (it) => it.name);
*
* assertEquals(sortedByName, [
* { name: "Anna" },
* { name: "John" },
* { name: "Kim" },
* ]);
* ```
*
* @example Usage with bigints
* ```ts
* import { sortBy } from "@std/collections/sort-by";
* import { assertEquals } from "@std/assert";
*
* const people = [
* { name: "Anna", age: 34n },
* { name: "Kim", age: 42n },
* { name: "John", age: 23n },
* ];
*
* const sortedByAge = sortBy(people, (person) => person.age);
*
* assertEquals(sortedByAge, [
* { name: "John", age: 23n },
* { name: "Anna", age: 34n },
* { name: "Kim", age: 42n },
* ]);
* ```
*
* @example Usage with Date objects
* ```ts
* import { sortBy } from "@std/collections/sort-by";
* import { assertEquals } from "@std/assert";
*
* const people = [
* { name: "Anna", startedAt: new Date("2020-01-01") },
* { name: "Kim", startedAt: new Date("2020-03-01") },
* { name: "John", startedAt: new Date("2020-06-01") },
* ];
*
* const sortedByStartedAt = sortBy(people, (people) => people.startedAt);
*
* assertEquals(sortedByStartedAt, [
* { name: "Anna", startedAt: new Date("2020-01-01") },
* { name: "Kim", startedAt: new Date("2020-03-01") },
* { name: "John", startedAt: new Date("2020-06-01") },
* ]);
* ```
*
* @example Using the index parameter
* ```ts
* import { sortBy } from "@std/collections/sort-by";
* import { assertEquals } from "@std/assert";
*
* const array = [2, 3, 1];
* const result = sortBy(array, (_, index) => -index);
*
* assertEquals(result, [1, 3, 2]);
* ```
*/
export function sortBy<T>(
iterator: Iterable<T>,
selector:
| ((el: T, index: number) => number)
| ((el: T, index: number) => string)
| ((el: T, index: number) => bigint)
| ((el: T, index: number) => Date),
options?: SortByOptions,
): T[] {
const array = Array.isArray(iterator) ? iterator : Array.from(iterator);
const len = array.length;
const selected: (string | number | bigint | Date)[] = new Array(len);
const indices: number[] = new Array(len);
for (let i = 0; i < len; i++) {
selected[i] = selector(array[i]!, i);
indices[i] = i;
}
const order = options?.order === "desc" ? -1 : 1;
indices.sort((ia, ib) => {
const a = selected[ia]!;
const b = selected[ib]!;
if (Number.isNaN(a)) return order;
if (Number.isNaN(b)) return -order;
return order * (a > b ? 1 : a < b ? -1 : 0);
});
const result: T[] = new Array(len);
for (let i = 0; i < len; i++) {
result[i] = array[indices[i]!]!;
}
return result;
}
|