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JavaScript Array findIndex() Method

The JavaScript array findIndex() method is used to return the index of the first element of the given array pass a test that satisfies the provided function condition. If no element satisfies the condition, it returns -1.

Syntax:

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

Parameter Values

Parameter

Description

function(currentValue, index, arr)

It Required a function to be run for each element in the array.
Function arguments:

Argument	Description
currentValue	It Required the current value of the element
index	This argument is optional and is used for the array index of the current element
arr	It is optional and is used for the array object the current element belongs to

thisValue

This parameter is optional and it is used for a value to be passed to the function to be used as its "this" value. The value "undefined" will be passed as its "this" value, If this parameter is empty

Browser Support

Method	Chrome	Edge	Firefox	Safari	Opera
findIndex()	45.0	12.0	25.0	7.1	32.0

Here is an example of JavaScript array findIndex() Method:

<!DOCTYPE html>
<html>
<body>
<button onclick="myFindIn()">Click me</button>
<p id="findin"></p>
<script>
var ages = [8, 15, 18, 25];
function checkAdult(age) {
  return age >= 18;
}
function myFindIn() {
  document.getElementById("findin").innerHTML = ages.findIndex(checkAdult);
}
</script>
</body>
</html>

Output:

Example 2:

<!DOCTYPE html>
<html>
<body>
<script>
var finin1=[5,22,19,25,34];
var result=finin1.findIndex(x=>x>20);
document.writeln(result)
</script>
</body>
</html>

Output:

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