findIndex method

The findIndex method allows you to find the index of the first element according to the callback passed in the parameter. If the element is not found, then -1 is returned.

Syntax

javascriptarray.findIndex(function);

Example

Let's find the index of the first even array element:

javascriptlet arr = [1, 2, 3, 4, 5];

let res = arr.findIndex(function (elem){
  return elem % 2 == 0;
});

console.log(res);

The code execution result:

javascript1

Example

And now let's set such conditions in the function, which will not match any element in an array:

javascriptlet arr = [1, 2, 3, 4, 5];

let res = arr.findIndex(function (elem){
  return elem < 0;
});

console.log(res);

The code execution result:

javascript-1

See also