The array["exist", "not exist"] contains "selector or xpath of element must exist (for some lazyload element)" & "selector or xpath of element must not exist (for some loading placeholder which need scroll into view to load)"
"waitElement": [ ".summary", "#popular.fade:not(.in)" ]
Repeated checking before ".summary" excite and "#popular.fade:not(.in)" do not exist.
When you set 'waitElement', it's same as the 'wait', that means current rule will effect when url is matched. You can leave a "" when you don't want to set "exist" or "not exist", when you set a "not exist", pagetual will try to trigger lazy load of target element