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();  
        $('#btnAdministracao').css('display','block');
        //alert('User name:' + userObject.get_title() + '\n Login Name:' + userObject.get_loginName());  
    }  
    function onFailureMethod(sender, args) {  
       //alert('request failed ' + args.get_message() + '\n' + args.get_stackTrace());  
    }