t
raf(function () {...}), делай raf.call(MainElement, function () {...})и да, вот ссылки на mdn про
bind, call и applybind - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_objects/Function/bindcall - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/callapply - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply
Теперь вроде понятно как привязать this

