Sum function.

snippets.js

@@ -27,6 +27,14 @@ Array.prototype.include = function(value) {
     return false;
 };
 
+Array.prototype.sum = function() {
+    var sum = 0;
+    for(var i=0;i<this.length;i++) {
+        sum += (parseFloat(this[i]) || 0);
+    }
+    return sum;
+};
+
 Array.prototype.allGroupings = function() {
     if (this.length == 0) {
         return [];  /* short-circuit the empty-array case */