The find() method returns a value of an element in the typed array, if it satisfies the provided testing function. Otherwise undefined is returned. TypedArray is one of the typed array types here.

See also the findIndex() method, which returns the index of a found element in the typed array instead of its value.

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find(callbackFn, thisArg)



A function to execute for each element in the typed array. It should return a truthy value to indicate a matching element has been found, and a falsy value otherwise. 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 array find() was called upon.

thisArg Optional

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

Return value

A value in the array if an element passes the test; otherwise, undefined.


The find() method executes the callbackFn function once for each element present in the typed array until it finds one where callbackFn returns a true value. If such an element is found, find() immediately returns the value of that element. Otherwise, find() returns undefined. 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.

callbackFn is invoked with three arguments: the value of the element, the index of the element, and the typed array object being traversed.

If a thisArg parameter is provided to find(), it will be used as the this for each invocation of the callbackFn. If it is not provided, then undefined is used.

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

The range of elements processed by find() is set before the first invocation of callbackFn. Elements that are appended to the typed array after the call to find() begins will not be visited by callbackFn. If an existing, unvisited element of the typed array is changed by callbackFn, its value passed to the visiting callbackFn will be the value at the time that find() visits that element's index; elements that are deleted are not visited.


Find a prime number in a typed array

The following example finds an element in the typed array that is a prime number (or returns undefined if there is no prime number).

function isPrime(element, index, array) {
  let start = 2;
  while (start <= Math.sqrt(element)) {
    if (element % start++ < 1) {
      return false;
  return element > 1;

const uint8 = new Uint8Array([4, 5, 8, 12]);
console.log(uint8.find(isPrime)); // 5


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

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See also