1//The findIndex() method returns the index of the first element 
2//in the array that satisfies the provided testing function.
3//Otherwise, it returns -1, indicating that no element passed the test.
4const array1 = [5, 12, 8, 130, 44];
5
6const isLargeNumber = (element) => element > 13;
7
8console.log(array1.findIndex(isLargeNumber));
9// expected output: 3
10

1const array1 = [5, 12, 8, 130, 44];
2const search = element => element > 13;
3console.log(array1.findIndex(search));
4// expected output: 3
5
6const array2 = [
7  { id: 1, dev: false },
8  { id: 2, dev: false },
9  { id: 3, dev: true }
10];
11const search = obj => obj.dev === true;
12console.log(array2.findIndex(search));
13// expected output: 2

1// find index of array item; test values using a function
2const arr = ['A','B','C'];
3const index = arr.findIndex((item) => item === 'B');	// index == 1

1// 	findIndex(callback fn)  
2
3//	.... return index (when condition meets)
4//  .... return -1 (if condition not meets)
5
6const array = [5, 12, 8, 130, 44];
7
8/// it returns the index of number which satisfy the condition true
9const index = array.findIndex((item)=> item>10);   //1
10
11/// now we can check what element at that index...
12console.log(array[index]); // array[1]

1const array1 = [5, 12, 8, 130, 44];
2const search = element => element > 13;
3console.log(array1.findIndex(search));
4
5const array2 = [
6  { id: 1, dev: false },
7  { id: 2, dev: false },
8  { id: 3, dev: true }
9];
10const search = obj => obj.dev === true;
11console.log(array2.findIndex(search));