JS: Dollar Sign in JavaScript

Many JavaScript library use dollar sign $ as the name of their primary function.

The dollar sign is allowed character of identifier. [see Allowed Characters in Identifier]

This practice seems to have started with the Prototype JavaScript Framework, then other libraries picked it up, in particular jQuery. [see jQuery Tutorial by Example]

JavaScript spec 1999 suggests that the dollar sign should be used for generated code:

However, JavaScript spec year 2011, no longer says that.

This standard specifies specific character additions: The dollar sign ($) and the underscore (_) are permitted anywhere in an IdentifierName.

ECMAScript 5.1 §7#sec-7.6