In mobile Safari js doesn't work at all?

Question

JavaScript

Tested only on mobile Safari on iPhone 5s. All other browsers and devices are fine.
Burger doesn't work (on all pages)
"Write to managers" button doesn't work here (popup should open) Tabs
don't work here , here and here
Animation doesn't work here in the timeline (this can be fixed by connecting wow)
In general, damn it, count nothing at all does not work. I already have no idea what to do, please tell me at least where to look :)

UPD: slick works safely

Answer 1

The problem was in using letinsteadvar

Answer 2

Could it be flexbox? Where you indicated, flexbox is used everywhere. Maybe safari is old