function checkUsername(username,path,option){expression=/(&\B)|(^&)|(#\B)|(^#)/;if(expression.exec(username)){username='erro';}
try{xmlhttp=new XMLHttpRequest();}catch(e){try{xmlhttp=new ActiveXObject("Msxml2.XMLHTTP");}catch(e){try{xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");}catch(e){xmlhttp=false;}}}
if(xmlhttp){xmlhttp.onreadystatechange=function(){if(xmlhttp.readyState==4){if(xmlhttp.status==200){document.getElementById("checkUsername").innerHTML=xmlhttp.responseText;}}}
xmlhttp.open('GET',path+'/search_username.php?option='+option+'&username='+username,true);xmlhttp.send(null);}}