Lark.js - a port of the Lark parsing toolkit to Javascript

Lark is a parsing toolkit for Python, built with a focus on ergonomics, performance and modularity.

With Lark.js, you create a fast Javascript parser from a grammar written for Lark.

The compiled Javascript modules include Lark's base classes and utilities, such as Tree, Transformer, and InteractiveParser.

Currently, only LALR(1) is supported. (Earley support is planned!)

Quick links

• Lark (Python)
• Cheatsheet (PDF)
• Online IDE
• Gitter chat

Install Lark.js

$ pip install lark-js --upgrade

Generate a Javascript LALR(1) parser

	python -m lark-js my_grammar.lark -o my_parser.js

For help, run:

	python -m lark-js --help

Syntax Highlighting

Lark provides syntax highlighting for its grammar files (*.lark):

• Sublime Text & TextMate
• vscode
• Intellij & PyCharm
• Vim
• Atom

List of main features

• Builds a parse-tree (AST) automagically, based on the structure of the grammar
• LALR(1) parser - Fast and light
• EBNF grammar
• Usable in the browser and in Node
• Automatic line & column tracking
• Standard library of terminals (strings, numbers, names, etc.)
• Import grammars from Nearley.js (read more)
• And much more!

License

Lark.js uses the MIT license.

Contribute

Lark.js is accepting pull-requests. If you would like to help, open an issue or find us on gitter.

Sponsoring

Lark.js was made possible with the help of a generous donation by Smore ❤️

If you like Lark, and want to see it grow, please consider sponsoring us!