<!--start javascript here

function isEmpty(s)
{   return ((s == null) || (s.length == 0));
}

function warnInvalid (theField, s)
{   theField.focus();
    theField.select();
    alert(s);
    return false;
}

function checkQty (theField)
{   if (isEmpty(theField)) return false;
    var Period = theField.value.lastIndexOf('.');
	var Length = theField.value.length;
	var IntPart = theField.value;
	if (Period != -1) 
    {   
       var Power  = Length - 1 - Period;
	   for (i = 0; i < Power; i++) 
	   {
	      IntPart = IntPart * 10;
	   }
    }
//	alert (Period + "*" + Length + "*" + IntPart);
	if (!isIntegerInRange (IntPart, 1, 999)) 
    {
	   return warnInvalid (theField, "This number is not valid. Please re-enter it now.");
    }
	else return true;
}

function isIntegerInRange (s, a, b)
{   var i; 
    for (i = 0; i < s.length; i++)
    {   
        var c = s.charAt(i);
        if (!((c >= "0") && (c <= "9"))) return false;
    }
    var num = parseInt (s);
    return ((num >= a) && (num <= b));
}

function springCalc(form) {
   //validate all quantities are entered

   var rider_weight = form.rider_weight.value;
   var weight_in = form.weight_in.value;
   var shock_travel = form.shock_travel.value;
   var wheel_travel = form.wheel_travel.value;
   // alert( rider_weight + "*" + weight_in + "*" + shock_travel + "*" + wheel_travel);
   var sp_5th_spring = 0;
   var sp_rsf_spring = 0;
   var fourb_5th_spring = 0;
   var fourb_rsf_spring = 0;
   var wcc = 1;                               // weight conversion constant
   if (weight_in == "kg") wcc = 1;
   if (weight_in == "st") wcc = 14 / 2.2;     // 6.363636
   if (weight_in == "lbs") wcc = 1 / 2.2;     //  .454545
   
   var sp_5th_factor = 4;                     // multiplying factor
   var sp_rsf_factor = 4.5;
   var fourb_5th_factor = 4.4;
   var fourb_rsf_factor = 4.9;
   var ride_type = form.ride_type.value;      // plush33 or freeride28
   if (ride_type == "freeride28") {
	  sp_5th_factor = 4.3;                     
      sp_rsf_factor = 4.8;
      fourb_5th_factor = 4.7;
      fourb_rsf_factor = 5.2;
   }
   // alert( ride_type + "*" + sp_5th_factor + "*" + sp_rsf_factor + "*" + fourb_5th_factor + "*" + fourb_rsf_factor);

   sp_5th_spring = Math.round((rider_weight * wcc * sp_5th_factor) / shock_travel * ( wheel_travel / shock_travel));
   sp_rsf_spring = Math.round((rider_weight * wcc * sp_rsf_factor) / shock_travel * ( wheel_travel / shock_travel));
   fourb_5th_spring = Math.round((rider_weight * wcc * fourb_5th_factor) / shock_travel * ( wheel_travel / shock_travel));
   fourb_rsf_spring = Math.round((rider_weight * wcc * fourb_rsf_factor) / shock_travel * ( wheel_travel / shock_travel));
   
   form.sp_5th_spring.value = sp_5th_spring; 
   form.sp_rsf_spring.value = sp_rsf_spring;
   form.fourb_5th_spring.value = fourb_5th_spring;
   form.fourb_rsf_spring.value = fourb_rsf_spring;
   
   form.rider_weight.value = rider_weight;
   form.weight_in.value = weight_in;
   form.shock_travel.value = shock_travel;
   form.wheel_travel.value = wheel_travel;
   
   return true;
}

// End of script validation -->