$是函数，可以称为-$().

$()的行为在很大程度上取决于所提供的参数，尽管下面的所有示例都会返回一个jQuery对象.它可以:

The behaviour of $() varies immensely depending on the parameters supplied, although all examples below will return a jQuery object. It can:

1. 注册document.ready处理程序-$(myfunc)
2. 充当选择器 -
3. 构造元素-$('<div>')
4. 返回一个空对象-$()

1. register a document.ready handler - $(myfunc)
2. act as a selector - $('#myid')
3. construct elements - $('<div>')
4. return an empty object - $()

$也是一个对象，其中包含各种实用程序功能$.each，例如该对象的 properties .在这种情况下，这些功能就像 namespace 一样.

$ is also an object that contains various utility functions $.each, etc as properties of that object. In this context, it acts like a namespace for those functions.