A simple JS to determine if a user is restricted by GFW with jQuery

ifInWall.js

var icon = "http://s.ytimg.com/yts/img/favicon-vfldLzJxy.ico";
var locationWall = (! $('<img src="'+ icon +'">').load()); // false if out of Mainland; true otherwise
if(locationWall)
{
  console.log("You are restricted by the Wall.")
}