blob: 119b09ba8344cf9cf0d829dd4c52dbb2791ddc1c [file] [log] [blame]
/**
* @license
* Copyright (C) 2017 The Android Open Source Project
*
* 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
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @param fn An iteratee function to be passed each element of
* the array in order. Must return a promise, and the following
* iteration will not begin until resolution of the promise returned by
* the previous iteration.
*
* An optional second argument to fn is a callback that will halt the
* loop if called.
*/
export function asyncForeach<T>(
array: T[],
fn: (item: T, stopCallback: () => void) => Promise<unknown>
): Promise<T | void> {
if (!array.length) {
return Promise.resolve();
}
let stop = false;
const stopCallback = () => {
stop = true;
};
return fn(array[0], stopCallback).then(() => {
if (stop) {
return Promise.resolve();
}
return asyncForeach(array.slice(1), fn);
});
}