How to hover over images from grey to color

I’ve been trying to add a hover effect over my social media icons in the footer of my page. I am following this tutorial: https://webdesignerwall.com/tutorials/html5-grayscale-image-hover/comment-page-6

This is what I’ve done:
1. Uploaded the greyscale_to_color.js to my server
2. I’ve place this directly into my footer to bring the script into the footer:
<script src="greyscale_to_color.js" type="text/javascript"></script>
3. I’ve changed the “.item img” from original tutorial file to “#social-icons img”

This did not work. Is there somewhere else I should be placing my javascript?
Here is my website: https://www.essencia-spa.com