在JavaScript中？没什么特别的。它只是字符串的一部分。

In JavaScript? Nothing special. It is just part of a string.

$ 函数可能会对它做一些事情，但很难说 $ 函数是什么。

The $ function might do something with it, but it is hard to tell what the $ function is.

有很多库提供 $ 函数，它充当该库的厨房接收器。它们包括原型， Mootools 和 jQuery 。这个看起来最像jQuery，在这种情况下，参数是一个包含 CSS选择器，所以＃表示 id选择器。

There are a lot of libraries which provide a $ function that acts as a kitchen sink for that library. They include Prototype, Mootools and jQuery. This one looks most like jQuery, in which case the argument is a string containing a CSS selector, so the # indicates the start of an id selector.

此选择具有给定id属性的单个元素。

This "Selects a single element with the given id attribute".