TypedArray.prototype.filter()

The filter() method creates a new typed array with all elements that pass the test implemented by the provided function. This method has the same algorithm as Array.prototype.filter(). TypedArray is one of the typed array types here.

Syntax

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

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

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

Parameters

callbackFn
Function to test each element of the typed array. Invoked with arguments (element, index, array). Return true to keep the element, false otherwise.
thisArgOptional
Value to use as this when executing callbackFn.

Return value

A new typed array with the elements that pass the test.

Description

The filter() method calls a provided callbackFn function once for each element in a typed array, and constructs a new typed array of all the values for which callbackFn returns a value that coerces to true. callbackFn is invoked only for indexes of the typed array which have assigned values; it is not invoked for indexes which have been deleted or which have never been assigned values. Typed array elements which do not pass the callbackFn test are skipped, and are not included in the new typed array.

callbackFn is invoked with three arguments:

  1. the value of the element
  2. the index of the element
  3. the typed array object being traversed

If a thisArg parameter is provided to filter(), 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.

filter() does not mutate the typed array on which it is called.

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

Examples

Filtering out all small values

The following example uses filter() to create a filtered typed array that has all elements with values less than 10 removed.

function isBigEnough(element, index, array) {
  return element >= 10;
}
new Uint8Array([12, 5, 8, 130, 44]).filter(isBigEnough);
// Uint8Array [ 12, 130, 44 ]

Filtering typed array elements using arrow functions

Arrow functions provide a shorter syntax for the same test.

new Uint8Array([12, 5, 8, 130, 44]).filter(elem => elem >= 10);
// Uint8Array [ 12, 130, 44 ]

Specifications

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

Browser compatibility

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See also