count empty values in array

Question

Given an array:

var arr = [1,,2,5,6,,4,5,6,,];

Count how many empty values is has: (length - length after removing the emp

Answer 1

Looks good to me.

You could also do:

var empties = arr.reduce(function(x, y){ return x-1; }, arr.length);

Also, if you don't mind sorting the array, you might get a little added performance out of:

arr.sort();
for (var j=arr.length-1; j > 0 && arr[j] === undefined; j--) {}
var empties = arr.length-j-1;