Explanation input only numeric

Question

I'm new in html and javascript, coming from C#. Now I have created an input field, which must only accept numeric input. Like so:

<input name="numemp" type="text" id="numemp" value="<%=numberofemp%>" maxlength="10" onkeypress="return isNumberKey(event)" />

And I found this javascript:

function isNumberKey(evt) 
{
    var charCode = (evt.which) ? evt.which : event.keyCode;
    if (charCode != 46 && charCode > 31 && (charCode < 48 || charCode > 57)) 
    {
        return false;
    }
    else 
    {
        return true;
    }      
}

This is not clear for me, I get it that the code checks the pressed key is numeric. And if it is numeric it returns true. But where does the code ignores the input? I only see a return false when this happend...

In javascript `return false` means that default action of event (in this case - write character into input) will not be called. — bemol, Dec 09 '14 at 08:08
you can check this http://stackoverflow.com/questions/1639338/why-does-returning-false-in-they-keydown-callback-does-not-stop-the-button-click . — caslaner, Dec 09 '14 at 08:08

cнŝdk · Answer 1 · 2014-12-09T09:36:09.560

0

Yes indeed it doesn't ignore the input it just says whether it's a number or not, I think you don't need to use this function :

You only need HTML5 pattern to do it pattern="[0-9]+" and it will be automatically managed:

<input name="numemp" type="text" id="numemp" value="<%=numberofemp%>" maxlength="10" pattern="[0-9]+" />

Take a look at HTML pattern Attribute for further information.

edited Dec 09 '14 at 09:36

answered Dec 09 '14 at 08:19

cнŝdk

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This does not answer the question, which asked for an explanation for some code. It could have been posted as a comment. – Jukka K. Korpela Dec 09 '14 at 09:21
@JukkaK.Korpela Yes you're right, but I've only thought it'll be a better solution for this issue – cнŝdk Dec 09 '14 at 09:33

Explanation input only numeric

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