// By Chris van Marle (C.A.vanMarle@inter.NL.net - http://www.chrisworld.org)
<!-- Begin
FormName  = "form"  
CheckName = "check" 
TextName  = "text" 

var Condition=new Array(
'a!=""', // simple validation (must be filled)
'a!=""', // simple validation (must be filled)
'a!=""&&a.length>5&&a.indexOf("@")!=-1&&a.indexOf(".")!=-1', // validation for email address
'a.length>7&&!(a.split("/")[0]*1>12)&&!(a.split("/")[1]*1>31)&&!(a.split("/")[2]*1<1900)' // validation for date
);
function docheck(w) {
eval("a=document." + FormName + "." + TextName + w + ".value");
if (eval(Condition[w])) eval("document." + FormName + "." + CheckName + w + ".checked=true");
else eval("document." + FormName + "." + CheckName + w + ".checked=false");
}
//  End -->