JavaScript Array findIndex() method

The JavaScript array findIndex() method returns the index of first element of the given array that satisfies the provided function condition.

The findIndex() method executes a function for each array element.

The findIndex() method returns the index (position) of the first element that passes a test.

The findIndex() method returns -1 if no match is found.

In this tutorial, you will learn how to use the Array findIndex() method to find the first element that satisfies a given test.

The findIndex() method does not execute the function for empty array elements.

The findIndex() method does not change the original array.

Syntax

array.findIndex(callbackFunction(currentValue, index, arr), thisValue)

• callbackFunction– Required. A function to run for each array element. It represents the function that test the condition.
• currentValue– Required. The current element of array.
• index – It is optional. The index of current element.
• arr – It is optional. The array on which findIndex() operated.
• thisValue– It is optional. The value to use as this while executing callback. Default undefined.

Return Value

• Returns the index of the first element in the array that satisfies the given function.
• Returns -1 if none of the elements satisfy the function.

Example

const array1 = [5, 12, 8, 130, 44];

const isLargeNumber = (element) => element > 13;

console.log(array1.findIndex(isLargeNumber));
// expected output: 3