Javascript Numeric Form Validation

Question

I made a simple little calculator for math class. It does simple things like find volumes and areas of certain shapes, but saves me a lot of time in homework.

I uploaded it to the internet for my classmates, but I figured I would make the forms only be able to have numbers in them. I found some answers on tizag, but I don't really understand those solutions.

I'm looking for something like this:

function calculation() {
    if (form.thenumbers.value = code to check if it is numeric)
    {
        calculations
    } else {
        alert("Numbers only please");
    }
}

If it can't be that simple, I just appreciate a little explanation to how any other way works. Thanks.

stackoverflow.com/questions/18082/…

c69
– c69

2012-03-11 02:49:06 +00:00
Commented Mar 11, 2012 at 2:49 — c69
– c69, Commented Mar 11, 2012 at 2:49

Chris Sobolewski · Accepted Answer · 2012-03-11 02:53:49Z

1

 if (form.thenumbers.value.match(/^[\d]*$/)){
     //do stuff
 }

Should work for you. This will match the value for a 0 or more digits. If you would like it to match for 1 or more, use + in place of *.

answered Mar 11, 2012 at 2:53

Chris Sobolewski

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2 Comments

Jack Davis Over a year ago

Thanks, and just to be clear at the form.thenumbers part, I would put formname.name of specific form, and what would I do if it is one input without a whole form?

Chris Sobolewski Over a year ago

If your form markup was <form name="calculator"><input type='text' name='number'></form> you could use document.calculator.number.value to get the value.

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