Home > @rushstack/node-core-library > Async > mapAsync
This API is provided as a preview for developers and may change based on feedback that we receive. Do not use this API in a production environment.
Given an input array and a
callback function, invoke the callback to start a promise for each element in the array. Returns an array containing the results.
static mapAsync<TEntry, TRetVal>(iterable: Iterable<TEntry> | AsyncIterable<TEntry>, callback: (entry: TEntry, arrayIndex: number) => Promise<TRetVal>, options?: IAsyncParallelismOptions | undefined): Promise<TRetVal>;
|iterable||Iterable<TEntry> | AsyncIterable<TEntry>||the array of inputs for the callback function|
|callback||(entry: TEntry, arrayIndex: number) => Promise<TRetVal>||a function that starts an asynchronous promise for an element from the array|
|options||IAsyncParallelismOptions | undefined||(Optional) options for customizing the control flow|
an array containing the result for each callback, in the same order as the original input
This API is similar to the system
Array#map, except that the loop is asynchronous, and the maximum number of concurrent promises can be throttled using IAsyncParallelismOptions.concurrency.
callback throws a synchronous exception, or if it returns a promise that rejects, then the loop stops immediately. Any remaining array items will be skipped, and overall operation will reject with the first error that was encountered.