language-javascript

Parser for JavaScript

https://github.com/erikd/language-javascript

LTS Haskell 23.27:0.7.1.0
Stackage Nightly 2025-07-12:0.7.1.0
Latest on Hackage:0.7.1.0

See all snapshotslanguage-javascript appears in

BSD-3-Clause licensedbyAlan Zimmerman
Maintained byErik de Castro Lopo
This version can be pinned in stack with:language-javascript-0.7.1.0@sha256:3c68380fc4794475ff4ebec608f8cf7ce9b15b9b69eb938d423f8aafdefbe0d7,3865
Used by 1 package inlts-23.17(full list with versions):

Parser for JavaScript

Build Status

Based (loosely) on language-python

Two Versions

There are currently two versions:

  • 0.5 series : Is a continuation of the 0.5.X.Y series, from the [master](https://github.com/erikd/language-javascript/tree/master) branch of thisgithub repository.

  • 0.6 and 0.7 series : This has a vastly different and improved AST which makes if farmore difficult to build an non-sensical Javascript AST. This code is in thenew-ast branch ofthis github repository.

How to build

Make sure your locale supports UTF-8. For example, on most Unix-like platforms,you can type:

export LC_ALL=en_US.UTF-8

Library:

cabal clean && cabal configure && cabal build

Tests:

cabal clean && cabal configure -fbuildtests && cabal build

Running the tests

./dist/build/runtests/runtests

To debug the grammar

happy -iparse.txt -g -a  -d src/Language/JavaScript/Parser/Grammar5.y

This generates src/Language/JavaScript/Parser/Grammar5.hs, delete thiswhen done with the debug version

UTF8/Unicode version

Alex 3.0 now supports unicode natively, and has been included as adependency in the cabal file.

Note: The generation of the lexical analyser has been separated out,to remove the install-time dependency on Alex. If any changesneed to be made to the lexer, the Lexer.x source lies insrc-dev, and the runalex.sh script will invoke Alex with theappropriate directories.

Changes

ChangeLog forlanguage-javascript

0.7.1.0 – 2020-03-22

  • Add support forasync function specifiers andawait keyword.

0.7.0.0 – 2019-10-10

  • Add support for (Ryan Hendrickson):
    • Destructuring in var declarations
    • const in for statements
    • ES6 property shorthand syntax
    • Template literals
    • Computed property names
    • Bare import declarations
    • Exotic parameter syntaxes
    • Generators andyield
    • Method definitions
    • classes- super keyword

0.6.0.13 – 2019-06-17

  • Add support for (Cyril Sobierajewicz):
    • Unparenthesized arrow functions of one parameter
    • Export from declarations
    • Add back support for identifiers namedas

0.6.0.12 – 2019-05-03

  • Add support for for..of and friends (Franco Bulgarelli)