How to detect changes in TinyMCE?

I’m late to the party, but for future reference here is how you do it in TinyMCE 4.X:

tinyMCE.init({
   setup:function(ed) {
       ed.on('change', function(e) {
           console.log('the event object ', e);
           console.log('the editor object ', ed);
           console.log('the content ', ed.getContent());
       });
   }
});