TypedArray.prototype.forEach()

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.

Syntax

// Arrow function
forEach((element) => { ... } )
forEach((element, index) => { ... } )
forEach((element, index, array) => { ... } )

// Callback function
forEach(callbackFn)
forEach(callbackFn, thisArg)

// Inline callback function
forEach(function callbackFn(element) { ... })
forEach(function callbackFn(element, index) { ... })
forEach(function callbackFn(element, index, array){ ... })
forEach(function callbackFn(element, index, array) { ... }, thisArg)

Parameters

callbackFn

Function that produces an element of the new typed array, taking three arguments:

element

The current element being processed in the typed array.

index

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

array

The array forEach() was called upon.

thisArg Optional

Value to use as this when executing callbackFn.

Return value

undefined.

Description

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.

Examples

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

Specifications

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

Browser compatibility

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See also