rj parses a superset of JSON similar to the notation used in Knockout data-bind attributes. outback.js uses rj to parse its data-bind attributes and to revive unobtrusive data bindings.

tl;dr

x = location: 'http://news.ycombinator.com'
y = rj.parse 'attr: { href: @location }', x
expect(y.attr.href).toBe(x.location)

.parse

The parse method accepts a text and an optional resolver, and produces a JavaScript object. A resolver is either an object used to bind symbol literals to values, or a function used to rewrite the object.

text = 'cats: "the best!"'

o = rj.parse text, (k, value) ->
    if value and value.hasOwnProperty('cats')
        value.dogs = value.cats
        delete value.cats

    value

expect(o.dogs).toBe("the best!");

.revive

The revive method applys a resolver to a source object to produce a "revived" object.

resolver = location: 'http://news.ycombinator.com'

parsedObj = rj.parse 'attr: { href: @location }'
revivedObj = rj.revive parsedObj, resolver

expect(revivedObj.attr.href).toBe(resolver.location)

.rewrite

The rewrite method accepts a text and applies a series of regular expression transformations to rewrite it as a valid JSON text.

Regular Expressions?! Now you have two problems...

rj is based off Crockford's json2.js which uses the same technique. You can see the still-beating heart of his work in the parse method.

What sorts of texts are supported?

Any valid JSON text

o = rj.parse '{ "book": { "title": "The Grapes of Wrath", author: "John Steinbeck" } }'

Texts where a symbol literals appears in value positions

A symbol literal is a legal JavaScript identifier prefixed by an @ character.

o = rj.parse '{ "book": { "title": @title, "author": @author } }'

Outer braces are optional

o = rj.parse '"book": { "title": @title, "author": @author }'

Quotes are optional for JavaScript identifiers in key positions

o = rj.parse 'book: { title: @title, author: @author }'

It's a bit too heavy for me and/or I don't need to match Unicode symbols

Yes, the symbol literal and unquoted key parsing code works by looking for legal JavaScript identifiers which, as you probably know, are defined in terms of Unicode categories. However, as you also probably know, the built in regular expression engine does not support the \p{Category} script, so I've included all the ranges in expanded form. This support balloons the file size to 30kb dev, 15 kb minified.

If you don't need support for Unicode identifiers, use rj.enUS.js (11kb dev, 3kb minified) which matches identifiers using ([$_a-zA-Z][$_a-zA-Z0-9])* instead.

License

The MIT License

Copyright (c) 2012 David Zarlengo 

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.