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

Or, without using js 1.6 filter/foreach, you could cycle it yourself this way:

var arr = [1,,2,5,6,,4,5,6,,];
var emptyElems = 0;
for(var i=0, l = arr.length; i < l; i++){
    emptyLength += (arr[i] === undefined) ? 1 : 0;
}

alert(emptyElems); //alerts 3