Field with UPPERCASE but without soecial characters

[diririck]

I hardly have any experience in programming....
a bit with javascript.

Now I am trying to make a form in which I want to force the input to be in a specific way.

No special characters and only uppercase.
I manage to get only 1 of those or uppercase or no special characters.... but not both.

What I have up until now is for Uppercase:
<input name="eigencode" type="text" size=30 maxlength="25"onChange="javascript:this.value=this.value.toUpperCase();" input name=EigenCode type="text" size=30 maxlength="25" value="Vul hier jouw code in.">

For "no" special characters:
//"checkExp(this,/^[\-A-Za-z\d]+$/)"

How do I combine these two ?

Thanks for anyone who wants to help.