The array or array like object of elements to be searched.
A asynchronous or synchronous function that accepts up to three arguments. arrForEach calls the callbackfn function one
time for each element in the array.
OptionalthisArg: anyAn object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, null or undefined the array will be used as the this value.
arrForEachAsync supports either a synchronous or asynchronous (returns a Promise) callback function. If the callback function returns
a Promise then the next iteration will not be called until the promise is resolved. If the callback function returns a Promise that is
rejected then the iteration will stop and the promise returned by arrForEachAsync will be rejected with the same error.
const items = ['item1', 'item2', 'item3', 'item4', 'item5', 'item6', 'item7', 'item8', 'item9', 'item10'];
const copyItems = [];
arrForEachASync(items, (value, index) => {
copyItems.push(value);
if (index === 5) {
return -1; // Stop the iteration
}
});
console.log(copyItems); // ['item1', 'item2', 'item3', 'item4', item5']
// Also supports input as an array like object
const items = { length: 3, 0: 'item1', 1: 'item2', 2: 'item3' };
// Asynchronous examples using await
const items = ['item1', 'item2', 'item3', 'item4', 'item5', 'item6', 'item7', 'item8', 'item9', 'item10'];
const copyItems = [];
await arrForEachASync(items, (value, index) => { // Note: DO NOT use async here unless you use await within the function
if (index < 5) {
// Logs each iteration index
// Logs each value
console.log(value);
// Returning a promise will cause `arrForEachAsync` to return a promise to the caller
// and wait for the promise to resolve before calling the callback function again.
return createTimeoutPromise(10, true);
}
return -1; // Stop the iteration
});
console.log(copyItems); // ['item1', 'item2', 'item3', 'item4', item5']
Calls the provided
callbackFnfunction once for each element in an array (or ArratLike) instance in ascending index order. It is not invoked for index properties that have been deleted or are uninitialized. And unlike the ES6 forEach() this supports async functions and you CAN stop or break the iteration by returning -1 from thecallbackFnfunction.The range (number of elements) processed by arrForEach() is set before the first call to the
callbackFn. Any elements added beyond the range or elements which as assigned to indexes already processed will not be visited by thecallbackFn.The
callbackFnmay executesynchronouslyorasynchronouslyand if thecallbackFnreturns aPromisethen the next iteration will not be called until the promise is resolved. If thecallbackFnreturns aPromisethat is rejected then the iteration will stop and the promise returned by arrForEachAsync will be rejected with the same error.