.findIndex(

const array1 = [5, 12, 8, 130, 44];
const findLargeNumber = element => element > 13;
console.log(array1.findIndex(findLargeNumber));
// expected output: 3

const array2 = [{id:1, dev:false}, {id:2, dev:false}, {id:3, dev:true}];
const WheresTheDev = obj => obj.dev === true;
console.log(array2.findIndex(WheresTheDev));
// expected output: 2

var fruits = ["Banana", "Orange", "Apple", "Mango"];
return fruits.indexOf("Apple"); // Returns 2

array.findIndex(call back function)

 //index of ............
 //first