Keyvalidation

[danasegarane76]

Hi all,I am using the following javascript code to restrict the entry to alphanumeric

function issueentry(){  if((event.keyCode >= 97 && event.keyCode <= 122) || (event.keyCode >= 65 && event.keyCode <= 90) ||(event.keyCode >= 48 && event.keyCode <= 57) ) 	 //alert(event.keycode);  ;  else 	 event.keyCode = 0;	}

I want this code also allow the special charcters "& and : " to be allowed.How can I Improve this code to get my aim

[danasegarane76]

or How can I implement validation of only the following letters charcters A-Z,a-z,0-9,&,: