Why does isNaN for form input true for a string only if I enter quotes around it?
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I've seen this in JavaScript in numerous examples but I can't get this to work for me. I must be overlooking something, so I would appreciate a kind soul helping me out here because I am new to JavaScript:

     spend=eval(form.spend.value);
     if(isNaN(num)) {
         alert('I am not a number');
     }

The above form input is gathered from:
     <input type=text name=spend value="" size=6 STYLE="background-color: #EDEDE8;">

If I enter in abc as input, the alert I am not a number doesn't display. If I enter "abc" with quotes around is, it does display the alert.

I am checking input from the form where the user should only be allowed to enter numbers. Only numbers should be accepted. Thank you!

