LocomotiveScroll and ScrollTrigger - error when onLeaveBack and locoScroll.scrollTo

[pranastons]

Help! I need scroll to 'some_element' when i leave some-section. For this I used event onLeaveBack. (

onLeaveBack: () => locoScroll.scrollTo('.some_element') ,

) and I get this error
(

ScrollTrigger.js:453 Uncaught TypeError: Cannot read property 'update' of undefined
    at _updateAll (ScrollTrigger.js:453)
    at eval (locomotive-scroll.esm.js:401)
    at Array.forEach (<anonymous>)
    at _default.checkEvent (locomotive-scroll.esm.js:398)
    at _default.dispatchScroll (locomotive-scroll.esm.js:356)
    at _default.checkScroll (locomotive-scroll.esm.js:241)
    at _default.checkScroll (locomotive-scroll.esm.js:2043)
    at eval (locomotive-scroll.esm.js:1995)

)
If I used event onEnter - all ok, but I need do scroll when I scrolling up

[GreenSock]

What version of ScrollTrigger are you using? Can you please provide a minimal demo? It's just super difficult to troubleshoot blind

 

Also, you don't have once: true, do you? 

[pranastons]

See the Pen jOqbqob by _evgeniya_ (@_evgeniya_) on CodePen.

[pranastons]

I can resolve this problem like this (

onEnterBack: () => {);

                    locoScroll.off("scroll", ScrollTrigger.update);

                    locoScroll.scrollTo('.some_element', 0, 700);

                    locoScroll.on("scroll", ScrollTrigger.update);

                }

)
but I think than but I think that this no right (it's a crutch)

 

I use gsap v - 3.4.2

[GreenSock]

That looks to me like you're creating a race condition that'll crash the browser because inside your ScrollTrigger's update, you're forcing the LocomotiveScroll to a totally different value which will update the ScrollTrigger which will update the LocomotiveScroll and around and around you go. It's like an infinite loop; a logic problem. See what I mean? So yes, if you want to escape the logic problem, you'd need to remove the listener like you did in your proposed fix. 

[pranastons]

Thank. I think I understand what you mean. 
But I don't understand why such an error does not occur on the event onEnter ???

[ZachSaucier]

4 hours ago, pranastons said:

I don't understand why such an error does not occur on the event onEnter ???

onEnter fires once before the new value is set; there's no loop. An onUpdate that changes the value will continuously fire in a loop.