/* Checks if the value is a valid positive number */
function IsNumeric(value) {
    var ValidChars = "0123456789";
    var IsNumber = true;
    var Char;

    for (i = 0; i < value.length && IsNumber == true; i++) {
        Char = value.charAt(i);
        if (ValidChars.indexOf(Char) == -1) {
            IsNumber = false;
        }
    }
    
    return IsNumber;
}

/* Adds the product to the cart */
function AddToCart(quantity, productId) {
    if (IsNumeric(quantity)) {
        var argument = productId + "#" + quantity;
        var postback = document.getElementById("hfPostBackReference").value;
        postback = postback.replace("#argument#", argument);
        eval(postback);
    }
}