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Re: JavaScript Case Project 3-1: The dreaded NaN error

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dmn2004404@gmail.com wrote:
> Wait -- WAIT! I think I got it -- almost. I've had to make a few
> changes, as follows. Here's my revised JavaScript: 
> 
> <script type="text/javascript">
> var shipping, total;
> function calculateShipping(purchasePrice) {
>     if (purchasePrice <= 25)
>         shipping = 1.50;
>     else
>         shipping = purchasePrice * .10;
>     total = purchasePrice + shipping;
>      window.alert('Purchase price plus shipping and handling is $' +
>      total); 
> }
> </script>
> 
> and the revised input tag for the button:
> 
> <input type="submit" name="btnCalculate" id="btnCalculate"
> value="Calculate"
> onclick="calculateShipping(parseFloat(txtPurchasePrice.value,10))" /> 
> 
> I believe the key was actually to put the value of the text box INSIDE
> the calculateShipping() function as a parameter. 
> 
> Anyway, with these revisions, I tried the 123.45 value you attempted,
> and I got the LONG floating value of 135.79500000000002 -- which
> looked a little messy. So I attached the "toFixed(2)" method to
> "totalCost" at the end of the "window.alert" command, and it worked. 
> 
> But now, I'd like to validate user box input so that if the user
> should enter a zero, a negative number, or something that actually IS
> "NaN" (e.g. "Hello world!"), the page will produce a dialog box that
> says the value is invalid. How might I go about doing that? 

Make the calculateShipping function to return a boolean value. Returns 
true to allow submit or false to disallow it. i.e.: due to invalid form 
input(s).

Also check for NaN result each and every parseFloat using isNaN.

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JavaScript Case Project 3-1: The dreaded NaN error dmn2004404@gmail.com - 2012-11-11 08:28 -0800
  Re: JavaScript Case Project 3-1: The dreaded NaN error "Mel Smith" <med_cutout_syntel@aol.com> - 2012-11-11 10:08 -0700
    Re: JavaScript Case Project 3-1: The dreaded NaN error dmn2004404@gmail.com - 2012-11-11 09:34 -0800
      Re: JavaScript Case Project 3-1: The dreaded NaN error "Mel Smith" <med_cutout_syntel@aol.com> - 2012-11-11 10:56 -0700
        Re: JavaScript Case Project 3-1: The dreaded NaN error dmn2004404@gmail.com - 2012-11-11 10:07 -0800
        Re: JavaScript Case Project 3-1: The dreaded NaN error dmn2004404@gmail.com - 2012-11-11 10:52 -0800
          Re: JavaScript Case Project 3-1: The dreaded NaN error JJ <jaejunks@glegooilma-swapit.com> - 2012-11-11 20:15 +0000
            Re: JavaScript Case Project 3-1: The dreaded NaN error dmn2004404@gmail.com - 2012-11-11 12:45 -0800
          Re: JavaScript Case Project 3-1: The dreaded NaN error JJ <jaejunks@glegooilma-swapit.com> - 2012-11-11 20:11 +0000
        Re: JavaScript Case Project 3-1: The dreaded NaN error dmn2004404@gmail.com - 2012-11-11 12:15 -0800
          Re: JavaScript Case Project 3-1: The dreaded NaN error Osmo Saarikumpu <osmo@weppipakki.com> - 2012-11-12 10:10 +0200
  Re: JavaScript Case Project 3-1: The dreaded NaN error Gregor Kofler <usenet@gregorkofler.com> - 2012-11-12 09:51 +0100
    Re: JavaScript Case Project 3-1: The dreaded NaN error Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-11-12 11:49 +0100

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