List of Acorn contributors. Updated before every release.

Adrian Heine

Adrian Rakovsky

Alistair Braidwood

Amila Welihinda

Aparajita Fishman

Arian Stolwijk

Artem Govorov

Boopesh Mahendran

Bradley Heinz

Brandon Mills

Charles Hughes

Charmander

Chris McKnight

Conrad Irwin

Daniel Tschinder

David Bonnet

Domenico Matteo

ehmicky

Eugene Obrezkov

Felix Maier

Forbes Lindesay

Gilad Peleg

impinball

Kevin Irish

Kevin Kwok

krator

laosb

Marek

Marijn Haverbeke

Martin Carlberg

Rich Harris

Sebastian McKenzie

Shahar Soel

Sheel Bedi

Simen Bekkhus

Teddy Katz

Timothy Gu

Properly handle `allowAwaitOutsideFunction` in for statements.

Treat function declarations at the top level of modules like let bindings.

Don't allow async function declarations as the only statement under a label.

Make sure the walker and bin files are rebuilt on release (the previous release didn't get the up-to-date versions).

Fix crash in walker when walking a binding-less catch node.

Upgraded to Unicode 11.

In the walker, go back to allowing the `baseVisitor` argument to be null to default to the default base everywhere.

Fix regression when passing `null` as fourth argument to `walk.recursive`.

Fix a bug in the walker that caused a crash when walking an object pattern spread.

Allow U+2028 and U+2029 in string when ECMAVersion >= 10.

Allow binding-less catch statements when ECMAVersion >= 10.

Add `allowAwaitOutsideFunction` option for parsing top-level `await`.

A _second_ republish of the code in 5.5.1, this time with yarn, to hopefully get valid timestamps.

A republish of the code in 5.5.1 in an attempt to solve an issue with the file timestamps in the npm package being 0.

Fix regression in walker causing property values in object patterns to be walked as expressions.

Fix misleading error message for octal escapes in template strings.

Support object spread in the AST walker.

The identifier character categorization is now based on Unicode version 10.

Acorn will now validate the content of regular expressions, including new ES9 features.

5.4.0 somehow accidentally included an old version of walk.js.

Disallow duplicate or escaped flags on regular expressions.

Disallow octal escapes in strings in strict mode.

Add support for async iteration.

Add support for object spread and rest.

Fix parsing of floating point literals with leading zeroes in loose mode.

Allow duplicate property names in object patterns.

Don't allow static class methods named `prototype`.

Disallow async functions directly under `if` or `else`.

Parse right-hand-side of `for`/`of` as an assignment expression.

Stricter parsing of `for`/`in`.

Don't allow unicode escapes in contextual keywords.

Parsing class members was factored into smaller methods to allow plugins to hook into it.

Copyright (C) 2012-2018 by various contributors (see AUTHORS)

Permission is hereby granted, free of charge, to any person obtaining a copy

of this software and associated documentation files (the "Software"), to deal

[](https://travis-ci.org/acornjs/acorn)

[](https://www.npmjs.com/package/acorn)

[](https://cdnjs.com/libraries/acorn)

[Author funding status: ](https://marijnhaverbeke.nl/fund/)

Acorn is open source software released under an

[MIT license](https://github.com/acornjs/acorn/blob/master/LICENSE).

You are welcome to

[report bugs](https://github.com/acornjs/acorn/issues) or create pull

requests on [github](https://github.com/acornjs/acorn). For questions

and discussion, please use the

[Tern discussion forum](https://discuss.ternjs.net).

npm install acorn

Alternately, you can download the source and build acorn yourself:

git clone https://github.com/acornjs/acorn.git

cd acorn

npm install

npm run build

[estree]: https://github.com/estree/estree

- **ecmaVersion**: Indicates the ECMAScript version to parse. Must be

either 3, 5, 6 (2015), 7 (2016), 8 (2017), 9 (2018) or 10 (2019, partial

support). This influences support for strict mode, the set of

reserved words, and support for new syntax features. Default is 7.

declarations can only appear at a program's top level. Setting this

option to `true` allows them anywhere where a statement is allowed.

- **allowAwaitOutsideFunction**: By default, `await` expressions can only appear inside `async` functions. Setting this option to `true` allows to have top-level `await` expressions. They are still not allowed in non-`async` functions, though.

- **allowHashBang**: When this is enabled (off by default), if the

code starts with the characters `#!` (as in a shellscript), the

first line will be treated as a comment.

line. It accepts as arguments its input file and the following

options:

- `--ecma3|--ecma5|--ecma6|--ecma7|--ecma8|--ecma9|--ecma10`: Sets the ECMAScript version

to parse. Default is version 7.

- `--module`: Sets the parsing mode to `"module"`. Is set to `"script"` otherwise.

- [`acorn-jsx`](https://github.com/RReverser/acorn-jsx): Parse [Facebook JSX syntax extensions](https://github.com/facebook/jsx)

- [`acorn-objj`](https://github.com/cappuccino/acorn-objj): [Objective-J](http://www.cappuccino-project.org/learn/objective-j.html) language parser built as Acorn plugin

Plugins for ECMAScript proposals:

- [`acorn-stage3`](https://github.com/acornjs/acorn-stage3): Parse most stage 3 proposals, bundling:

- [`acorn-async-iteration`](https://github.com/acornjs/acorn-async-iteration): Parse [async iteration proposal](https://github.com/tc39/proposal-async-iteration)

- [`acorn-bigint`](https://github.com/acornjs/acorn-bigint): Parse [BigInt proposal](https://github.com/tc39/proposal-bigint)

- [`acorn-class-fields`](https://github.com/acornjs/acorn-class-fields): Parse [class fields proposal](https://github.com/tc39/proposal-class-fields)

- [`acorn-dynamic-import`](https://github.com/kesne/acorn-dynamic-import): Parse [import() proposal](https://github.com/tc39/proposal-dynamic-import)

- [`acorn-import-meta`](https://github.com/acornjs/acorn-import-meta): Parse [import.meta proposal](https://github.com/tc39/proposal-import-meta)

- [`acorn-numeric-separator`](https://github.com/acornjs/acorn-numeric-separator): Parse [numeric separator proposal](https://github.com/tc39/proposal-numeric-separator)

- [`acorn-optional-catch-binding`](https://github.com/acornjs/acorn-optional-catch-binding): Parse [optional catch binding proposal](https://github.com/tc39/proposal-optional-catch-binding)

- [`acorn-private-methods`](https://github.com/acornjs/acorn-private-methods): parse [private methods, getters and setters proposal](https://github.com/tc39/proposal-private-methods)

- [`acorn5-object-spread`](https://github.com/adrianheine/acorn5-object-spread): Parse [Object Rest/Spread Properties proposal](https://github.com/tc39/proposal-object-rest-spread)

- [`acorn-object-rest-spread`](https://github.com/victor-homyakov/acorn-object-rest-spread): Parse [Object Rest/Spread Properties proposal](https://github.com/tc39/proposal-object-rest-spread)

- [`acorn-es7`](https://github.com/angelozerr/acorn-es7): Parse [decorator syntax proposal](https://github.com/wycats/javascript-decorators)

- [`acorn-static-class-property-initializer`](https://github.com/victor-homyakov/acorn-static-class-property-initializer): Partial support for static class properties from [ES Class Fields & Static Properties Proposal](https://github.com/tc39/proposal-class-public-fields) to support static property initializers in [React components written as ES6+ classes](https://babeljs.io/blog/2015/06/07/react-on-es6-plus)

#!/usr/bin/env node

var path = require('path');

var fs = require('fs');

var acorn = require('../dist/acorn.js');

var infile;

var forceFile;

var silent = false;

var compact = false;

var tokenize = false;

var options = {};

function help(status) {

var print = (status === 0) ? console.log : console.error;

print("usage: " + path.basename(process.argv[1]) + " [--ecma3|--ecma5|--ecma6|--ecma7|--ecma8|--ecma9|...|--ecma2015|--ecma2016|--ecma2017|--ecma2018|...]");

print(" [--tokenize] [--locations] [---allow-hash-bang] [--compact] [--silent] [--module] [--help] [--] [infile]");

process.exit(status);

for (var i = 2; i < process.argv.length; ++i) {

var arg = process.argv[i];

if ((arg === "-" || arg[0] !== "-") && !infile) { infile = arg; }

else if (arg === "--" && !infile && i + 2 === process.argv.length) { forceFile = infile = process.argv[++i]; }

else if (arg === "--locations") { options.locations = true; }

else if (arg === "--allow-hash-bang") { options.allowHashBang = true; }

else if (arg === "--silent") { silent = true; }

else if (arg === "--compact") { compact = true; }

else if (arg === "--help") { help(0); }

else if (arg === "--tokenize") { tokenize = true; }

else if (arg === "--module") { options.sourceType = "module"; }

else {

var match = arg.match(/^--ecma(\d+)$/);

if (match)

{ options.ecmaVersion = +match[1]; }

else

{ help(1); }

}

function run(code) {

var result;

try {

if (!tokenize) {

result = acorn.parse(code, options);

} else {

result = [];

var tokenizer$$1 = acorn.tokenizer(code, options), token;

do {

token = tokenizer$$1.getToken();

result.push(token);

} while (token.type !== acorn.tokTypes.eof)

}

} catch (e) {

console.error(e.message);

process.exit(1);

}

if (!silent) { console.log(JSON.stringify(result, null, compact ? null : 2)); }

if (forceFile || infile && infile !== "-") {

run(fs.readFileSync(infile, "utf8"));

} else {

var code = "";

process.stdin.resume();

process.stdin.on("data", function (chunk) { return code += chunk; });

process.stdin.on("end", function () { return run(code); });