function array_sum( array ) {	// Calculate the sum of values in an array
	// 
	// + original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
	var key, sum=0;
	// input sanitation
	if( !array || (array.constructor !== Array && array.constructor !== Object) || !array.length ){
		return null;
	}
	for(var key in array){
		sum += array[key];
	}
	return sum;
}

array_sum([4, 9, 182.6]);