How to make scroll to top button appear after scrolling

Question

This is how I include the button in the body:

<?php require_once('scrollToTop.php'); ?>

---

This is my scroll tTo Top.php file:

<div class="btnScrollToTop" data-scroll="up" type="button">
<img src="images/paudie_scroll_top_icon.jpg" alt="">

---

This is the CSS for the button:

.btnScrollToTop {
    position: fixed;
    right: 20px;
    bottom: 20px;
    width: 50px;
    width: 50px;
    border: none;
    z-index: 99;
}

---

This is my js file included in php footer as:

<script src="js/scroll.js"></script>

// JavaScript Document    
const btnScrollToTop = document.querySelector(".btnScrollToTop");

btnScrollToTop.addEventListener("click", function() {
    window.scrollTo({
        top: 0,
        left: 0,
        behavior: "smooth"
        });
        
    });

---

I am unable after a variety of attempts to get he button to appear only one the use has scroll 20px from the top of page.

Please help.

Answer 1

To do what you require you can retrieve the current window scroll position, check if it's higher than 20 and use it to toggle the display state of the button:

 const btnScrollToTop = document.querySelector(".btnScrollToTop"); // scroll to top of page when button clicked btnScrollToTop.addEventListener("click", e => { window.scrollTo({ top: 0, left: 0, behavior: "smooth" }); }); // toggle 'scroll to top' based on scroll position window.addEventListener('scroll', e => { btnScrollToTop.style.display = window.scrollY > 20? 'block': 'none'; });

 h3 { margin: 0 0 1000px; }.btnScrollToTop { position: fixed; right: 20px; bottom: 20px; width: 50px; border: none; z-index: 99; display: none; }

 <h3>Scroll down...</h3> <div class="btnScrollToTop" data-scroll="up" type="button"> <img src="images/paudie_scroll_top_icon.jpg" alt="Scroll to top" /> </div>

Answer 2

CSS:

.btnScrollToTop { 
  position: fixed; 
  right: 20px; 
  bottom: 20px; 
  width: 50px; 
  width: 50px; 
  border: none; 
  z-index: 99; 
  opacity: 0; 
}
.btnScrollToTop.active{  
  opacity: 1; 
}

JavaScript:

const btnScrollToTop = document.querySelector(".btnScrollToTop");
btnScrollToTop.addEventListener("click", function() { 
  window.scrollTo({ top: 0, left: 0, behavior: "smooth" }); 
}); 
window.addEventListener("scroll", () => { 
  if (window.pageYOffset > 100) { 
    btnScrollToTop.classList.add("active"); 
  } else { 
    btnScrollToTop.classList.remove("active"); 
  } 
});