Why build Javascript functions as jQuery plugins?

Question

I've seen alot of jQuery implementations of existent JavaScript functions that merely wrap the JavaScript code in a jQuery wrapper and don't actually rely on any of jQuery's base for their operation.

What are the benefits of using Javascript as a jQuery plugin?
If there are none is there a speed loss to use a jQuery plugin that could have easily been implemented outside the wrapper just as well?

Many thanks in advance (just trying to learn something here).

Updated with example:
http://plugins.jquery.com/project/base64
was originally
http://www.webtoolkit.info/javascript-base64.html

Answer 1

Much of jQuery is just a clever wrapper around existing JavaScript functions. $('#some-element') is perhaps a little easier to type than document.getElementById('some-element') but is otherwise not much different.

(I exaggerate, but only slightly.)

The main utility of jQuery is being able to combine together its various components. If I can select elements with a jQuery selector and then perform some action on those elements directly through a jQuery function, that's preferable to having to extract the underlying DOM elements and manipulate them manually, for example.

So it really depends on what functions you're seeing get wrapped. Some of them might very well add no value, and the authors are simply accustomed to everything being in jQuery. (We definitely see that phenomenon on StackOverflow — people who can't find a standard JavaScript function simply because it's not in the jQuery documentation). In other cases, there might be some hidden benefit even if the wrapper does little if anything to modify the underlying function's behavior.

Answer 2

There's also a lot of momentum around jQuery, and general trust. Including arbitrary javascript in your code base may not be as 'acceptable' to higher-up-types as including a new jQuery plugin.

So it may be a mistaken perception, but by being a jQuery plugin, a library benefits by being associated with high quality code.