jQuery

The jQuery is a lightweight cross browser JavaScript library, that helps work with:

• html/xml dom
• css
• events
• effects and animations
• ajax

One of the big advantages of jQuery is that it treats an array of elements as a single element. For example, you can assign a value to an attribute using the attr() method for each element.

Library can be downloaded from official site. Also library can be added to page from Google or Microsoft CDN. In this case a big chance that library already downloaded for other site and the browser will be used it from cache.

<!-- Google -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<!-- Microsoft -->
<script src="https://ajax.aspnetcdn.com/ajax/jQuery/jquery-3.4.1.min.js"></script>