How to ensure only valid numeric characters are entered into a textbox?
<p>Is there any existing jQuery functionality that can test if characters entered into a textbox are either numeric, or valid in a number?</p>

<p>Such as</p>

<p><code>.00</code> or <code>0.00</code>, but not <code>0.00.00</code> or <code>0a</code></p>

<p>What I'd like to do is catch any invalid characters before they appear in the textbox.</p>

<p>If it's not possible with jQuery, what's the best way to approach this?</p>

<p>I know with JavaScript I can test <code>isNaN()</code> and then return false, but that's going to start getting hairy when I have to account for all possible keystrokes.</p>
