JS: What does "quot; do?

Question

What does "

Answer 1

jQuery, and most javascript libraries use the $ as the primary base object (or function). Most of them also have a way to relinquish the $ so that it can be used with another library that uses it. In that case you use jQuery instead of $. In fact, $ is just a shortcut for jQuery.

Answer 2

Yes you got right! In general, the $ symbol was used to denote a jQuery object in JavaScript.

It's possible to wrap a DOM element into jQuery object or using a selector similar to CSS.

📖 Extra read
https://learn.jquery.com/using-jquery-core/jquery-object/

Answer 3

In JS '#x27; is just a valid character to start an identifier (a variable name), as well as '_' (underline) and any alphabetic character... All others character are ot valid for first character of identifier (but others, such as numeric) are valid if not at first position. That's also valid identifier to use it as unique character.

JQuery library (but not "most javascript libraries", maybe some, but I don't even believe) use '#x27; as the short primary base identifier.
Underscore library use '_' in a same way.

As @Zephy Koo specify, most of the time, presence of '#x27; in code denote the use of JQuery library, but not necessarly ;)