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.

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forEach(callbackFn, thisArg)



A function to execute for each element in the typed array. Its return value is discarded. The function is called with the following arguments:


The current element being processed in the typed array.


The index of the current element being processed in the typed array.


The typed array forEach() was called upon.

thisArg Optional

A value to use as this when executing callbackFn. See iterative methods.

Return value


The forEach() method executes the provided callbackFn 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.

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

forEach() executes the callbackFn 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


ECMAScript Language Specification
# sec-%typedarray%.prototype.foreach

Browser compatibility

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See also