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From: Stan Weiss <srweiss@erols.com>
Newsgroups: comp.lang.javascript
Subject: Re: How to Pass variable name to a function
Date: Wed, 11 Apr 2012 14:21:16 -0400
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Xref: csiph.com comp.lang.javascript:13337

Andreas Bergmaier wrote:
> 
> Stan Weiss schrieb:
> > save(stanForm.VD.value, AInput, 'Valve Diameter')"
> >
> > function save( field, vary, text ) {
> >       if( isNaN( field ) )
> >       {
> >          alert( text + " is not numeric" );
> >       }
> >       else
> >       {
> >           AInput = eval(field);  // this Works
> >           vary = eval(field);    // this does not workWorks
> >       }
> > }
> >
> > Can anyone see what I am doing wrong?
> 
> JavaScript does not have call-by-reference. Instead of passing a
> reference to the variable where the result should be stored, you pass
> the actual value of AInput to the function, where it gets the value of
> the local variable "vary". By assigning the result to vary, vary will
> get a new value. AInput is forgotten.
> 
> Also, you seem to try to parse a number with eval. Urghh. Use
> parseFloat() instead.
> 
> So, your code should be:
> 
> function numeric(field, fallback, name) {
>      var num = parseFloat(field);
>      if (isNaN(num)) {
>          alert(name + " is not numeric");
>          return fallback;
>      } else
>          return num;
> }
> AInput = numeric(stanForm.VD.value, AInput, 'Valve Diameter');
> 
> regards,
>   Bergi

Thanks for the reply Bergi. It now return the correct value but does not
function the way it did before. If a numeric and alpha are entered it
will take the numeric part and use it. I want it to show any error if
the field is not all numeric.

So I changed
      if (isNaN(num)) {
to
      if( isNaN( field ) )

Thanks again for your help
Best Regards
Stan