Uncaught TypeError: Cannot read property '_throttled' of undefined

[cindychaopeng]

Uncaught TypeError: Cannot read property '_throttled' of undefined thrown at

throttle:function(a,b,e){b._throttled||(b.apply(this,e),b._throttled=setTimeout(function(){b._throttled=!1},a.value||250))}

Looks a undefined check should be done on b.