Use Variable Instead Of Number For Function Input?

I'm using simpleCart() javascript shopping machine for my page.The script accepts values in a specific syntax:onclick="simpleCart.add('name=Some name','price=23.4','quantity=1');"But because the price of the product is not always the same but comes up after previously made calculations, i want to parse the values in simpleCart() through another function. I have made the following one which gets the price from a textbox (resultAlmires) of a form (Almires), then converts it to american format (. instead of ,) makes it have one decimal only and finally parse it to simpleCart() with the use of a variable.However it doesn't seem to work:

function addAlmiri() {
var timi = document.Almires.resultAlmires.value;
timi = timi.replace(/,/,".");

[code]....