JavaScript parser in JavaScript

Question

I need to add some lightweight syntactic sugar to JavaScript source code, and process it using a JavaScript-based build system. Are there any open source JavaScript parsers written in JavaScript? And are they reasonably fast when run on top of V8 or a similar high-performance JavaScript implementation?

Thank you for any pointers you can provide!

"I need to add some lightweight syntactic sugar to JavaScript source code" You do? Like what? — Peter Bailey, Mar 31 '10 at 16:15
Objective-J does that. you might want to checkout its open sourced code. But it uses a totally different syntax similar to Objective-C and interprets to Javascript at runtime afaik. — Anurag, Mar 31 '10 at 16:31
JSLint contains a JavaScript parser written in JavaScript. See http://www.jslint.com/fulljslint.js Around line 2049 begins the parser. JSLint is written to also handle html so you'd have to gloss over those parts. — Crescent Fresh, Mar 31 '10 at 17:03
Crescent French: Please repost your comment as an answer, and I'll vote you up. Thank you! — emk, Mar 31 '10 at 21:15
The source code for jslint is available on GitHub: https://github.com/douglascrockford/JSLint => https://github.com/douglascrockford/JSLint/blob/master/jslint.js — dmitris, Dec 06 '13 at 13:47

score 33 · Answer 1 · answered Sep 26 '11 at 07:43

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UglifyJS (JS compressor/beautifier in JavaScript) contains a complete JavaScript parser that exposes a simple API. It's heavily tested and used in some big projects (WebKit).

answered Sep 26 '11 at 07:43

mishoo

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UglifyJS is great and thank you for it. Thanks also for HTMLArea, which was a great reference for me when developing a WYSIWYG editor around 7 or 8 years ago. I would suggest mentioning your interest when linking to UglifyJS though. – Tim Down Jan 26 '12 at 23:48
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I'd just like to point out that this parser is ready to go, and seems to work perfectly. It's contained in a separate file, so no need to wade through jslint.js to take out parts you don't need. +1 – tex Feb 22 '12 at 10:46

Johannes Gerer · Answer 2 · 2016-05-12T14:06:38.527

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The fastest Javascript parser in Javascript was esprima.

It also gives you

Sensible format for the abstract syntax tree (AST), compatible with Mozilla Parser API

edited May 12 '16 at 14:06

answered Aug 05 '12 at 09:01

Johannes Gerer

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score 24 · Accepted Answer · edited Jan 07 '12 at 05:40

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Crescent Fresh answered this question in the comments:

JSLint contains a JavaScript parser written in JavaScript. See JSlint by Douglas Crockford Around line 2712 begins the parser. JSLint is written to also handle html so you'd have to gloss over those parts

edited Jan 07 '12 at 05:40

Ivan Castellanos

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answered Apr 13 '10 at 13:59

emk

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Crescent Fresh, if you'd like to repost your comment as an answer, I'll accept it and upvote you. – emk Apr 13 '10 at 14:00
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Recent source code, above link went 404: https://github.com/douglascrockford/JSLint – sibidiba May 13 '11 at 17:34
Answer updated (https://github.com/douglascrockford/JSLint/blob/master/jslint.js) – Ivan Castellanos Jan 07 '12 at 05:41

score 13 · Answer 4 · answered Sep 18 '13 at 15:04

acorn is a really fast JavaScript parser written in JavaScript. It's even faster than esprima now. The results I got in Chrome form esprima's speed comparison page:

Source            Esprima    UglifyJS2    Traceur    Acorn
Underscore 1.4.1  15.1       23.8         14.2       7.6
Backbone 1.0.0    17.1       30.2         16.7       7.9
jQuery 1.9.1      241.1      247.2        125.4      81.4
Total             273.3 ms   301.2 ms     156.3 ms   96.9 ms

It's compatible with Mozilla's Parser API, so you can use escodegen to generate JavaScript from the parse trees.

score 9 · Answer 5 · answered Mar 31 '10 at 16:43

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It's not a JavaScript parser itself, but there's a project called Jison (like Bison) for generating parsers that's written in JS.

answered Mar 31 '10 at 16:43

alunny

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Well, the question **was** for a JavaScript parser...?? – Sep 05 '16 at 08:10

score 7 · Answer 6 · answered Mar 31 '10 at 16:51

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The only metacircular interpreter that I have seen implemented in JavaScript is the Narcissus Engine.

It was developed also by Brendan Eich, they used a lot of non-standard extensions that are specific to SpiderMonkey, I think it will not work on V8.

answered Mar 31 '10 at 16:51

Christian C. Salvadó

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Interesting! I suppose there's a parser hiding in there somewhere. :-) Unfortunately, I'm looking for something that runs under V8. But thanks for the very interesting link! – emk Mar 31 '10 at 21:17

score 5 · Answer 7 · answered Oct 14 '12 at 00:45

Microsoft has developed the TypeScript compiler in TypeScript. Since TypeScript is a strict superset of JavaScript, and TypeScript compiles to JavaScript, the resulting compiler is technically a JavaScript compiler written in JavaScript.

That of course depends upon your definition of "compiler". But if a compiler accepting a superset of language A is not a language A compiler, that excludes GCC, Clang and pretty much every other compiler.

score 3 · Answer 8 · answered Oct 13 '12 at 12:32

https://developer.mozilla.org/en-US/docs/SpiderMonkey/Parser_API:

Recent builds of the standalone SpiderMonkey shell include a reflection of the SpiderMonkey parser, made available as a JavaScript API.

Note that this is only an API in JavaScript, the parser is C++.

Pavel Vlasov · Answer 9 · 2016-03-09T13:59:44.407

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JS/CC - The LALR(1) parser and lexical analyzer generator for JavaScript, written in JavaScript - http://jscc.phorward-software.com/

edited Mar 09 '16 at 13:59

answered Jun 23 '12 at 00:46

Pavel Vlasov

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Link works since latest edit – Shawn Apr 27 '16 at 12:14

JavaScript parser in JavaScript

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