Directions: Edit the bold text in the embed code box above the change the drawing shape, color ext..
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
body {
height: 2000px;
background: #f1f1f1;
}
#mySVG {
position: fixed;
top: 15%;
width: 400px;
height: 210px;
margin-left:-50px;
}
</style>
<svg id="mySVG">
<path fill="none" stroke="black" stroke-width="3" id="triangle" d="M150 0 L75 200 L225 200 Z"></path>
Sorry, your browser does not support inline SVG.
</svg>
<script>
// Get the id of the <path> element and the length of <path>
var triangle = document.getElementById("triangle");
var length = triangle.getTotalLength();
// The start position of the drawing
triangle.style.strokeDasharray = length;
// Hide the triangle by offsetting dash. Remove this line to show the triangle before scroll draw
triangle.style.strokeDashoffset = length;
// Find scroll percentage on scroll (using cross-browser properties), and offset dash same amount as percentage scrolled
window.addEventListener("scroll", myFunction);
function myFunction() {
var scrollpercent = (document.body.scrollTop + document.documentElement.scrollTop) / (document.documentElement.scrollHeight - document.documentElement.clientHeight);
var draw = length * scrollpercent;
// Reverse the drawing (when scrolling upwards)
triangle.style.strokeDashoffset = length - draw;
}
</script>