The jQuery's andSelf() method belongs to the core jQuery's methods that work with DOM traversing. Essentially, this method allows us to merge together two wrapped sets into a single wrapped set. This is useful especially when we use other DOM traversal methods, such as next() or nextAll(). For example, given the following HTML structure:
<h1 id="title">Lorem ipsum</h1> <h2>Dolor</h2> <h2>Sit amet</h2>
We want to select the heading next to the first one, add a CSS class to it and, at the same time, add that class also to the first heading. Here's how we can do:
$(document).ready(function() {
$('#title').next().andSelf().addClass('test');
});
This tells jQuery to add the next element and include also the selector that actually starts the selector chain. You can see an example below.