When we use Destructive Method to select and filter the wrapper set, a new result set will be generated. For example:
html
$lt;div$gt;
$lt;p$gt;Paragraph$lt;/p$gt;
$lt;p$gt ;Paragraph$lt;/p$gt;
$lt;/div$gt;
For the above DOM Tree, of course you can use
$('div').find ('p')
to get the p elements contained in all div elements, but the selection result will definitely not include the div element itself.
If you call andSelf() in a chain after find, you can also include previous selection($('div')) in the result set.
Usage example
For the above html code, use
$('div').find('p').css('border', '1px solid # 993300');
The css effect can only be applied to p elements
But if andSelf() is added after find(), the css effect will also be applied to all div elements