Making a popup login box or popup box with jQuery

http://www.ericbieller.com/2012/01/05/jquery-tutorial-making-a-login-popupdropdown-box-fade-in-with-only-jquery-and-css/

var mouse_inside = false;
$(document).ready(function() {
    $(".login_link").click(function() {
        var loginBox = $("#login_popupbox");
        if (loginBox.is(":visible"))
            loginBox.fadeOut("fast");
        else
            loginBox.fadeIn("fast");
        return false;
    });
 
    $("#login_popupbox").hover(function(){
        mouse_inside=true;
    }, function(){
        mouse_inside=false;
    });
 
    $("body").click(function(){
        if(! mouse_inside) $("#login_popupbox").fadeOut("fast");
    });
});