Sum of array elements?

programming flash
1

Hi, new to this forum so hi to all

I am stuck when trying to total the elements in an array, I keep getting NaN and cannot for the life of me see what I am doing wrong.

I am using a prototype function:


Array.prototype.sum = function(){
 var totalSum:Number,a=0;
 while(a<this.length){
  totalSum+=this[a];
  a++;
 }
 return totalSum;
}

var testArray:Array=Array(5,5,5,5,5,5,5,5,5,5);

trace(testArray.sum());

this gives me NaN

any help most appreciated!