The forEach() method executes a provided function once per array element. This method has the same algorithm as Array.prototype.forEach(). TypedArray is one of the typed array types here.


<var>typedarray</var>.forEach(<var>callback</var>[, <var>thisArg</var>])


Function that produces an element of the new typed array, taking three arguments:
The current element being processed in the typed array.
The index of the current element being processed in the array.
The array forEach() was called upon.
Optional. Value to use as this when executing callback.

Return value



The forEach() method executes the provided callback once for each element present in the typed array in ascending order. It is not invoked for indexes that have been deleted or elided. However, it is executed for elements that are present and have the value undefined.

callback is invoked with three arguments:

  • the element value
  • the element index
  • the typed array being traversed

If a thisArg parameter is provided to forEach(), it will be passed to callback when invoked, for use as its this value.  Otherwise, the value undefined will be passed for use as its this value. The this value ultimately observable by callback is determined according to the usual rules for determining the this seen by a function.

The range of elements processed by forEach() is set before the first invocation of callback. Elements that are appended to the typed array after the call to forEach() begins will not be visited by callback. If the values of existing elements of the typed array are changed, the value passed to callback will be the value at the time forEach() visits them; elements that are deleted before being visited are not visited.

forEach() executes the callback function once for each typed array element; unlike every() and some() it, always returns the value undefined.


Logging the contents of a typed array

The following code logs a line for each element in a typed array:

function logArrayElements(element, index, array) {
  console.log('a[' + index + '] = ' + element);

new Uint8Array([0, 1, 2, 3]).forEach(logArrayElements);
// logs:
// a[0] = 0
// a[1] = 1
// a[2] = 2
// a[3] = 3


Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of '%TypedArray%.prototype.forEach' in that specification.
Standard Initial definition.
ECMAScript 2017 Draft (ECMA-262)
The definition of '%TypedArray%.prototype.forEach' in that specification.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support ? 38 (38) ? ? ?
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support ? ? 38.0 (38) ? ? ?

See also


© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.

ECMAScript6 JavaScript Method Prototype Reference TypedArray TypedArrays