Check javascript compatibility with Internet explorer
Solved the issue by using JSHint (installed as package on Sublime Text 3) with option "esversion" set to 3 (compatibility with ECMAScript 3). This got me 90% of the way there and I did the rest manually.
I don't remember an "online code checking", but the most similar maybe are this two websites, can I use? and for Ecmascript.
Hope it helps!