[js]gsap timeline

gsap.registerPlugin(ScrollTrigger);
const txt = document.querySelectorAll("span")
const tl = gsap.timeline({}); 
txt.forEach(el => {
  tl.to(el,{
    scrollTrigger: {
    trigger : el,
    start:"0% center",
    end: "40% center",
    scrub:1,
  },
  opacity:1
  })
  .to(el,{
  scrollTrigger: {
    trigger : el,
    start:"60% center",
    end: "120% center",
    scrub:1,
  },
  opacity:0.1
  })
});