[bug] Page crash when used in IE11 with IE8 Compatability mode enabled

[bevand10]

Causes page crash when used in IE11 with IE8 Compatability mode enabled - corporate application

JS console reports document.addEventListener not available.

My workaround to skip loading Sortable if IE11 in Compatability mode

At the head of Socket.min.js (and Socket.js), add these two lines:

var proceed = (typeof document.addEventListener !== 'undefined')
if (proceed)

With this tweak, Sortable remains available for non-IE11/IE8Compatability users of the same corporate app.