Allowing numbers (and point) only in text box

[Kurrel]

Hi everyone,

 

I've got a list of input boxes into which only numeric values and a decimal point should be allowed.  I've managed to get what the key being pressed is, but exactly how to disallow it seems to be eluding me.  Returning false on the event doesn't stop the keypress.

 

What would you recommend in order to stop this?

 

(Or, more easily, is there a input type I am unaware of that already fills this role?)