Levelling Discount

levelling_discount.js

function getRealDiscount(stringDiscount){
	var real_discount = 0;

	var a = stringDiscount.split('+');
	
	for(var i=0;i<a.length;i++)
	{
		var x = 100;
		if(i != 0)
		{
			for(var j =0;j<i;j++)
			{
				x -= a[j]	
			}	
		}

		real_discount += x/100*a[i];
	}

	return real_discount;
}

getRealDiscount("10+20+30");