jquery - Why does Parralax scrolling not scroll at all on mobile? -

i developing first parralax website, reason on iphone doesn't scroll @ all. it's not question of animation or not, can't scroll anywhere, locked on first image.

i'm following tutorial: https://ihatetomatoes.net/simple-parallax-scrolling-tutorial/

i downloaded starting files , created same site works great on desktop nothing on mobile. why?

jquery , javascript runs @ slower frame rate on mobile due fact can memory heavy. trouble animations can slow or non existent. parallax effect checking on scroll position of browser window updates slower on iphone seems non responsive.

you can still achieve parallax effect if efficient coding effect never smooth on desktop.

if @ many mobile sites see stay away using many animation effects on mobile general idea streamline site can downloaded quickly.

i know doesn't hope gives bit of insight problem.