Mootool | Native Array Sum Value in Elements

calculatedTotalCost: function (subTotals)
{
var x = {subValue: 0};

subTotals.each(function(el, i) {
if(el.value)
{
this.subValue+= el.value;
}
}.bind(x));
var updateTotalCost = x.subValue;
this.totalCost.set('text', this.formatCurrency(updateTotalCost.toFixed(2)));
this.totalCost.set('value', updateTotalCost);
},