1 $ () function to receive a callback, as entry function (function execution after loading is complete tree dom) as:
$ ( Function () { / * * executing code * / })
2 $ () receiving the selector, the selector returns dom node corresponding to the object jQuery packaging, such as:
// naming jQuery usually wrapped object represents the beginning of $ var $ BTN = $ ( 'BTN #')
3 $ () received a dom object, and returns the wrapped object of dom jquery, use: ease of use can be jquery.fn all api function. Such as:
// BTN dom is the object var $ = $ BTN (BTN)
Incorrect please correct me