42 lines
1.8 KiB
JavaScript
42 lines
1.8 KiB
JavaScript
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const require_limitAsync = require("./limitAsync.js");
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const require_flatten = require("./flatten.js");
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//#region src/array/flatMapAsync.ts
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/**
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* Maps each element in an array using an async callback function and flattens the result by one level.
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*
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* This is equivalent to calling `mapAsync` followed by `flat(1)`, but more efficient.
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* Each callback should return an array, and all returned arrays are concatenated into
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* a single output array.
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*
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* @template T - The type of elements in the input array.
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* @template R - The type of elements in the arrays returned by the callback.
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* @param {readonly T[]} array The array to transform.
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* @param {(item: T, index: number, array: readonly T[]) => Promise<R[]>} callback An async function that transforms each element into an array.
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* @param {FlatMapAsyncOptions} [options] Optional configuration object.
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* @param {number} [options.concurrency] Maximum number of concurrent async operations. If not specified, all operations run concurrently.
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* @returns {Promise<R[]>} A promise that resolves to a flattened array of transformed values.
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* @example
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* const users = [{ id: 1 }, { id: 2 }];
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* const allPosts = await flatMapAsync(users, async (user) => {
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* return await fetchUserPosts(user.id);
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* });
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* // Returns: [post1, post2, post3, ...] (all posts from all users)
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*
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* @example
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* // With concurrency limit
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* const numbers = [1, 2, 3];
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* const results = await flatMapAsync(
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* numbers,
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* async (n) => await fetchRelatedItems(n),
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* { concurrency: 2 }
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* );
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* // Processes at most 2 operations concurrently
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*/
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async function flatMapAsync(array, callback, options) {
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if (options?.concurrency != null) callback = require_limitAsync.limitAsync(callback, options.concurrency);
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const results = await Promise.all(array.map(callback));
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return require_flatten.flatten(results);
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}
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//#endregion
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exports.flatMapAsync = flatMapAsync;
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