JavaScript TypedArray.prototype.findLast() Method

A new method, TypedArray.prototype.findLast(), was introduced in ECMAScript 2023 (ES2023). The method findLast() of instances TypedArray proceeds traverse over the typed array backwards and provides method returning the value of the first element that satisfies the supplied testing function. When there are no elements fulfilling the function criterion then it returns an undefined.

Syntax

findLast(callbackFn)

     OR

findLast(callbackFn, thisArg)

Parameter:

• callbackFn: A function that must be executed for each element in typed array, its return value will indicate whether or not a matching element has been found, the function is called with the following arguments-
  • element: It is the current element that findLast() was called upon on a typed array.
  • index: It is the index of current element which is being processed in the typed array.
  • array: The typed array findLast() was called upon.
• thisArg: (Optional) A value to use as this when executing callbackFn.

Return Type:

The highest index in an array that matches a given testing function otherwise, it will return undefined if no match found.

Example 1: In this example, we are finding last even number from an array.

const numbers = new Int8Array([-1, 2, 8, 5, 12, 3]);

const lastEven = 
  numbers.findLast(element => element % 2 === 0);

console.log(lastEven);

Output:

12

Example 2: In this example we are finding the element greater than 10.

const typedArray = new Uint8Array([5, 10, 15, 20, 25]);

const result = 
  typedArray.findLast(element => element > 10);

console.log(result);

Output:

25

Supported Browsers

• Chrome
• Edge
• Firefox
• Opera
• Safari