indexOf(“1”) returns -1 , when there is a 1 in my array

indexOf(“1”) returns -1 , when there is a 1 in my array.

I want to know where every position of “1” is, cause I want to eventually want to create a loop to count every how many time “1” is in the array.

var first_sudoku = [
  ["X", "X", "X", "X"],
  ["1", "X", "2", "X"],
  ["X", "1", "4", "X"],
  ["2", "X", "X", "1"],
];

function counter_for_numbers_in_chart(sudoku) {
  console.log(sudoku.indexOf("1"));
}

counter_for_numbers_in_chart(first_sudoku);

Answer

how about this:

first_sudoku.indexOf(first_sudoku[1])

and you get 1.

if you use:

first_sudoku.indexOf(first_sudoku[4])

you get -1