Clicking start will schedule two self-restarting functions:
runSetTimeout uses setTimeout(fn, 0) for queueing itself
runSetImmediate uses setImmediate(fn)
Results:
In IE10 Mobile, after a few seconds runImmediate is never called
In IE10 Desktop, after about 30s (once DOM manipulation has become slow enough) runImmediate is never called if you either: a) move the mouse around, or b) place the mouse on top of the changing log lines