With the older version 1.31, I was able to use JQuery from the ResourceLoader for my widgets with "(window.RLQ=window.RLQ||).push(".
This is not possible with version 1.34. I believe that it is because MW won't start the ResourceLoader until these widgets were ran. Sometimes those widgets work (if somehow these codes ran late) but normally won't.
I am using another widget to load JQuery at the start of the widgets as an interim solution for now, but it is supposed to be unnecessary.
One of my widgets make a XHR call every minute. The first call was initiated by that JQuery that I loaded, but subsequent calls were initiated by ResourceLoader.