JavaScript Array findLastIndex()

Definition and Usage

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

findLastIndex() The method returns the index (position) of the last element that passed the test.

If no matching element is found,findLastIndex() The method returns -1.

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

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

Instance

Example 1

Find the index of the last element with a value greater than 18:

const ages = [3, 10, 18, 20];
ages.findLastIndex(checkAge);
function checkAge(age) {
  return age > 18;
}

Try it yourself

Example 2

Find the index of the last element with a value greater than the input value:

<p><input type="number" id="toCheck" value="18"></p>
<button onclick="myFunction()">Test</button>
<p>Any values above: <span id="demo"></span></p>
<script>
const numbers = [4, 12, 16, 20];
function checkValue(x) {
  return x > document.getElementById("toCheck").value;
}
function myFunction() {
  document.getElementById("demo").innerHTML = numbers.findLastIndex(checkValue);
}
</script>

Try it yourself

Syntax

array.findLastIndex(function(currentValue, index, arr), thisValue)

Parameters

Return Value

Browser Support

findLastIndex() It is a feature of ES2023.

Since July 2023, all modern browsers support this method: