Get the Current Logged User name in sharepoint 2013 using JSON

<script src="/Style Library/scripts/jquery-1.10.1.min.js"></script>
<script type="text/javascript">
$(document).ready(function () {


var currentUser;
// Ensure that the SP.js is loaded
if (SP.ClientContext != null) {
  SP.SOD.executeOrDelayUntilScriptLoaded(getCurrentUser, 'SP.js');
}
else {
  SP.SOD.executeFunc('sp.js', null, getCurrentUser);
}

function getCurrentUser() {
   context = new SP.ClientContext.get_current();
    web = context.get_web();
  currentUser = web.get_currentUser();
  context.load(currentUser);
  context.executeQueryAsync(onSuccessMethod, onRequestFail);
}

function onSuccessMethod(sender, args) {
  var account = currentUser.get_loginName();

  var title = currentUser.get_title();

  currentUserAccount = account.substring(account.indexOf("|") + 1);

}

// This function runs if the executeQueryAsync call fails.
function onRequestFail(sender, args) {
 // alert('request failed' + args.get_message() + '\n' + args.get_stackTrace());
}


});
</script>