Sharepoint 2010 Find out Current Site access by Anonymous User Using Javascript

Using Ecma script we can find out user is logged in sharepoint site or not.

ExecuteOrDelayUntilScriptLoaded(getWebUserData, "SP.js");

function getWebUserData() {
context = new SP.ClientContext.get_current();
web = context.get_web();
this._currentUser = web.get_currentUser();
context.load(this._currentUser);
context.load(web, 'EffectiveBasePermissions');
context.executeQueryAsync(Function.createDelegate(this, this.onSuccessMethod),   Function.createDelegate(this, this.onFailureMethod));
}
function onSuccessMethod(sender, args) {

   // Put your jquery logic for Successfully login
}
function onfaiuremethod(sender, args) {
   alert('Anonymous User');
}

You can also get current user details using this code

ExecuteOrDelayUntilScriptLoaded(getWebUserData, "SP.js");
function getWebUserData() {
context = new SP.ClientContext.get_current();
web = context.get_web();

var userObject = web.get_currentUser();   

alert('User name:' + userObject.get_title() + '\n Login Name:' + userObject.get_loginName());  

}