JS: Make things happen OnScroll and create better interactive websites

Hello World! The fourth episode of the series - A CSS/JS trick in 5 minutes - Last Article was about a CSS trick (How to make a website responsive).
Since the last two articles were about a CSS trick, let's show you a Javascript one: How to make things happen on scroll.

The first method to make things happen on scroll is fairly easy:

window.onscroll = function () {
  // Code to happen on scroll here
};

But how underlined this query on stack overflow (I also tried this on a website) its result to cause lag and a longer charging time for the user. So it's better to use an event listener with a flag:

const animateFlag = true

window.addEventListener("scroll", function() {
  if(this.pageYOffset > 0) {
    if(animateFlag) {
      // Code to happen on scroll here
      animateFlag = false;
    }
  }
})

Var animateFlag block the code to rerun every time user scroll.

Hope this helped and thanks for reading!

Please smash that like button to make me understand that you want the series to continue :)

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