How do i use functions in scrollTrigger "start" option

[mfk]

Hello, im trying to use a function to return a dynamic number value for the  position of 'scroller-start' of my scroll trigger

 

// simplified scroll trigger here
ScrollTrigger.create({
  trigger: ".logo",
  start: "top DYNAMIC-VALUE-HERE",
  end: "+=500",
  scrub: 1,
});


// function to return dynamic value
function get_start() {
  return document.querySelector('.fixed-elements h2').offsetTop
}

 

I see that its possible to use functions in the start option, but how do use it only for the 2nd value as shown above?

[mvaneijgen]

create a variable which is placed out site of the string. 

 

start: "top " + DYNAMIC-VALUE-HERE,

 

Something like this should work. 

[ZachSaucier]

Hey mfk and welcome to the GreenSock forums.

 

2 hours ago, mfk said:

I see that its possible to use functions in the start option, but how do use it only for the 2nd value as shown above?

As mvaneijgen said, you can concatenate the value with a string. Using your function it should look something like this:

start: "top " + get_start(),

 

[mfk]

thanks! that sorted it out