Question

I want to disable users from entering a character into a HTML text input field that isnt a letter or number.

This exact functionality can be seen on the Twitter signup page (username field) https://twitter.com/signup.

Im trying to write this in jQuery. But i need to be able to grab the incomming keypress event value to test which key was pressed and if its value is acceptable.

Here’s the code:

<input type="text" id="username" name="username" />

<script type="text/javascript">
$("#username").keypress(function(event){   

 // Get the keypress value
 // ...?

// If the keypress value is illegal then disable it
if (...){
   event.preventDefault();
}

});
</script>

Answer 1

You can use the ‘which’ property of the event object to capture the keycode. You can use something like following code to get the corresponding character –

var c = String.fromCharCode(e.which);

See the link http://api.jquery.com/keypress/ for detailed explanation.