VS 2010 - Authentication (login Session) On The Clientsite

I am checking if the login session is still available on the client side in Jquery. What i did i created a web method to be called as a pagemethod on the client side. the webmethod is defined like this

[System.Web.Services.WebMethod]
public static Boolean CheckSessionExpiration()
{
Boolean IsLoggedin = false;
if (System.Web.HttpContext.Current.Session["LoginUser"] == null)
{
IsLoggedin = false;
HttpContext.Current.Session.Abandon();
HttpContext.Current.Response.Redirect("Login.aspx");
}
else
{
IsLoggedin = true;
}
return IsLoggedin;
}

and in my Jquery i have functions that perform different operations and before those function execute, i will need to make sure that the user is still logged in, so i will call the web method on the client side like this

PageMethods.CheckSessionExpiration(OnCheckSessionExpirationComplete);

and its callback function like this

function OnCheckSessionExpirationComplete(result) {
//Callback function
}

i know the webmethod should be void because the boolean value is not used at all on the client side or anywhere in the app. Now my question is. My Assumptions are , looking at the webmethod that is being called on the on the client side, it will execute first and if the session is null and it will not continue to execute. The client side code that was about to follow Please clear my assumption. Mybe there is something i don't know about Jquery that will make it continue even if the page redirection code is fired.