Getting the logged on user name using the client object model

If you want to use the SharePoint 2010 client object model you can use the code below:

ExecuteOrDelayUntilScriptLoaded(getWebUserData, “sp.js“);

    var context = null;

    var web = null;

    var currentUser = null; 

        function getWebUserData() { 

        context = new SP.ClientContext.get_current();

        web = context.get_web();

        currentUser = web.get_currentUser();

        currentUser.retrieve();

        context.load(web);

        context.executeQueryAsync(Function.createDelegate(this, this.onSuccessMethod), 

             Function.createDelegate(this, this.onFailureMethod));

   }

    function onSuccessMethod(sender, args) {

        var userObject = web.get_currentUser();

        var UserTitle = userObject.get_title();

        alert(UserTitle);

        }

    function onFailureMethod(sender, args) {

        alert(‘request failed ‘);

    }

Here is a video and a simple way to test it.