Why can't ES6 site see iPhones on Safari9?

Question

JavaScript

The people are squeaking on old Athos, the site is a white sheet.
Site 70% on es6.
Many Safari9 )))
But here it seems to be supported by 100% https://caniuse.com/#feat=es6-class
Wat de fak as they say ??
What else to check, where is the exit?

Answer 1

Take the trial https://www.browserstack.com/ and see what it says in the console. In general, without a poppy, sites on ios to test that still golovnyak
or here https://crossbrowsertesting.com/