esprima-derby (esprima.org, BSD license)
This fork of Esprima is modified to parse expressions in Derby templates.
Parsing of statements and other non-expression language features has been removed. With the exception of this, typeof, instanceof, in, and new, ECMAScript keywords have been removed. Expressions such as class and for are parsed as identifiers instead of as keywords.
Instead of parsing it as an identifier, undefined is parsed as a literal. It works the same way as null parsing.
Identifiers may start with an at sign (@) or hash (#) in addition to the standard set of starting characters (underscore, dollar sign, A-Z, a-z, and ISO 8859-1 or Unicode characters). These characters are not accepted as subsequent characters, which may only be the standard set (underscore, dollar sign, A-Z, a-z, ISO 8859-1 or Unicode characters, and 0-9).
For more information, see derbyjs.com and esprima.org.