window.onload = function(){
    
    if(document.getElementById("loginEmail") && document.getElementById("tip")){
	var email = document.getElementById("loginEmail");
	var tip = document.getElementById("tip");
    
	tip.style.display = "none";
	email.onfocus = function(){
	    tip.style.display = "block";
	}
	email.onchange = function(){
	    tip.style.display = "none";
	}
    }
}