This can be achieved by using recursion in javascript.
function countItems(arr, item) { // Write the code that goes here var count = 0; for(var i = 0; i < arr.length; ++i) { if(Array.isArray(arr[i])) { count +=countItems(arr[i], item); } else { if(arr[i] == item) count++; } } return count; } var arr = [ "apple", ["banana", "strawberry", "apple"], "apple", ["banana", "strawberry", ["banana", "strawberry", "apple"], "apple"] ]; console.log(countItems(arr, "apple")); //output