Accept the input and check the mask in the reverse way
<p>I need to develop an javascript function to check the mask reversely.
It means, 
if I set the mask "###:##",</p>

<ul>
<li>When I type "1" it shows, "1"<br> When I
type "2" it shows, "21"
<br> When I type "3"
it shows ,"3:21"<br>
etc..</li>
</ul>

<p>Is it possible to develop like that??
I have no idea how to start it? Can anyone put me on the right direction?</p>
