how can I do preview by ajax in same page ( see example )

hi ,

How can I do preview by ajax in same page

see here :
http://demos.arabiasolutions.com/webplus/topics/editor.html

write any thing and press on eye icon which is preview
and see

I see the code is :

$('.preview').click(function(){
			// $('#msgplus').keyup(function(){
				var Code = $("#msgplus").val();
				if(Code != '')
				{
					$.ajax({
						type: "POST",
						url: "http://demos.arabiasolutions.com/webplus/topics/editor_parser.html",
						data: 'topic=' + Code,
						cache: false,
						success: function(html){
							$("#msgplus_preview").html(html);
						}
					});
				}
			// });

Code (markup):

how ?