What does "$.something" mean in jquery?

i find it everywhere, like this.

function($) {
  开发者_如何转开发$.test = { some code }
}

what does it mean?

Think of $ just like any other variable. For jQuery, it's the jQuery object, which is pretty powerful. But it's just like any other variable; you could write your own $ if you wanted to, for example.

It's an unusual variable name, yes, but there's nothing magical about it. The .something is just a property of the variable $. It's no different than writing obj.something, except the variable name is $ instead.

The other non-alphanumeric character you can use in JavaScript as a variable name is _ (the underscore). It's used in some other libraries, like underscore.js . But again, there's nothing special about using _.

You should think about jQuery code as a division between two ways of calling functions:

1. Methods on selections. This is the standard "find some elements, do something with them" technique. It's code like $('p').val(), $('div').prepend(), etc.
2. Methods without selections. These are functions that don't require you to do a selection before calling a function. These are functions like $.ajax, $.param, $.each. For the sake of convenience, they are properties of the global variable $, which is the jQuery library. Often, they aren't jQuery-specific, but are useful pieces of code to include in the library.

the $ variable is an alias to the jQuery object / 'namespace'. So you when you see $.function() you are actually calling a method named 'function' on the jQuery object. In your example code provided an object named test is being attached to the jQuery object. if you wrote $.test = function() { } you would be attaching a function (method) instead of an object.

Go read the jQuery API and tutorials on their websites.

In particular "How it works" and "Plugin Authoring". As your code sample looks like a jQuery plugin