form, check if username exist

[Dennis_Gull]

Hello, I just started learning javascript and I need to use it on my register form. At the moment it will open an alert window if I write a username less then 6 letter and more then 10 but I would like to check if the username exist before you submit the form but Im not sure how to select the query and the use it in java.

PS:
Is there a way I can check if the person wrote thing I dont wont such as !"#¤%&/() and so on..

[thetestingsite]

You would need to use AJAX and a server side script to check if the username exists in the database already.

[Dennis_Gull]

bah, oh well I think I skip that then. At the moment I send the user back if its exist.

Anyways is there a way to check if the user use letter and shuch that I dont want?

[thetestingsite]

You could look into using Regular Expressions. Good to use for things like this.
Hope this helps.

[Twey]

But again, because Javascript can be bypassed, you need to do server-side checking too.