Simple JavaScript help

I have a simple javascript that I am using to do basic calculations in a web based lab system. Below is an example. The calculation works fine, but the result give way too many decimal places. Is there an easy way to truncate the number of decimal places displayed in the fields? I have tried using the toFixed(x) function, but am either not using it correctly or it will not work the way I need it to.

For this example, the user enters a value for totalVol in a text field and both the acidVol and waterVol fields are automatically populated with the calculated values. I am using onKeyUp= doIt(this.form) in each of the field because it is a form embedded within a form.

The formatting of the code looks a little strange because the system requires iXML formatting, so the "-" characters are just line continuations.

Any suggestions would be greatly appreciated.

Thanks in advance.

Code:

        script
          - function doIt(_b)
          - { if(_b.totalVol.value!="" )
          -   {
          -
          -   _b.acidVol.value=_b.totalVol.value/36.8;
          -   _b.waterVol.value=_b.totalVol.value - _b.acidVol.value;
          -
          -
          -  }
          - else {
          -        _b.acidVol.value="";
          -        _b.waterVol.value="";
          -       }  
          -
          - }
          - 

 

ex:
var t=1.123456;

var shortT=t.toFixed(3); //= 1.123

 

Thanks Kodo. Worked perfectly.