The $ dollar sign
Solution 1:
$
is just a name - names in JavaScript can contain dollar signs, and can consist of just a dollar sign.
Whether you use a dollar sign in your name isn't relevant to jQuery - there's nothing special about the dollar sign, except that jQuery defines a function called $
.
Solution 2:
I've seen it done both ways. All you are doing is creating a variable with the name '$selector', so they are functionally equivalent. The nice thing about it is that it does make them easy to pick out as jQuery objects.
Solution 3:
The cash sign is just an alias for the jQuery function. Starting the variable name with $ has no effect on that variable.
It is customary though, especially in jQuery plugin development, to use variables already wrapped in jQuery with a cash sign, so you know you can call jQuery methods, without having to wrap them.