## 8.12.0 (2024-06-14) ### New features Support ES2025 duplicate capture group names in regular expressions. ### Bug fixes Include `VariableDeclarator` in the `AnyNode` type so that walker objects can refer to it without getting a type error. Properly raise a parse error for invalid `for`/`of` statements using `async` as binding name. Properly recognize \"use strict\" when preceded by a string with an escaped newline. Mark the `Parser` constructor as protected, not private, so plugins can extend it without type errors. Fix a bug where some invalid `delete` expressions were let through when the operand was parenthesized and `preserveParens` was enabled. Properly normalize line endings in raw strings of invalid template tokens. Properly track line numbers for escaped newlines in strings. Fix a bug that broke line number accounting after a template literal with invalid escape sequences. ## 8.11.3 (2023-12-29) ### Bug fixes Add `Function` and `Class` to the `AggregateType` type, so that they can be used in walkers without raising a type error. Make sure `onToken` get an `import` keyword token when parsing `import.meta`. Fix a bug where `.loc.start` could be undefined for `new.target` `meta` nodes. ## 8.11.2 (2023-10-27) ### Bug fixes Fix a bug that caused regular expressions after colon tokens to not be properly tokenized in some circumstances. ## 8.11.1 (2023-10-26) ### Bug fixes Fix a regression where `onToken` would receive 'name' tokens for 'new' keyword tokens. ## 8.11.0 (2023-10-26) ### Bug fixes Fix an issue where tokenizing (without parsing) an object literal with a property named `class` or `function` could, in some circumstance, put the tokenizer into an invalid state. Fix an issue where a slash after a call to a propery named the same as some keywords would be tokenized as a regular expression. ### New features Upgrade to Unicode 15.1. Use a set of new, much more precise, TypeScript types. ## 8.10.0 (2023-07-05) ### New features Add a `checkPrivateFields` option that disables strict checking of private property use. ## 8.9.0 (2023-06-16) ### Bug fixes Forbid dynamic import after `new`, even when part of a member expression. ### New features Add Unicode properties for ES2023. Add support for the `v` flag to regular expressions. ## 8.8.2 (2023-01-23) ### Bug fixes Fix a bug that caused `allowHashBang` to be set to false when not provided, even with `ecmaVersion >= 14`. Fix an exception when passing no option object to `parse` or `new Parser`. Fix incorrect parse error on `if (0) let\n[astral identifier char]`. ## 8.8.1 (2022-10-24) ### Bug fixes Make type for `Comment` compatible with estree types. ## 8.8.0 (2022-07-21) ### Bug fixes Allow parentheses around spread args in destructuring object assignment. Fix an issue where the tree contained `directive` properties in when parsing with a language version that doesn't support them. ### New features Support hashbang comments by default in ECMAScript 2023 and later. ## 8.7.1 (2021-04-26) ### Bug fixes Stop handling `"use strict"` directives in ECMAScript versions before 5. Fix an issue where duplicate quoted export names in `export *` syntax were incorrectly checked. Add missing type for `tokTypes`. ## 8.7.0 (2021-12-27) ### New features Support quoted export names. Upgrade to Unicode 14. Add support for Unicode 13 properties in regular expressions. ### Bug fixes Use a loop to find line breaks, because the existing regexp search would overrun the end of the searched range and waste a lot of time in minified code. ## 8.6.0 (2021-11-18) ### Bug fixes Fix a bug where an object literal with multiple `__proto__` properties would incorrectly be accepted if a later property value held an assigment. ### New features Support class private fields with the `in` operator. ## 8.5.0 (2021-09-06) ### Bug fixes Improve context-dependent tokenization in a number of corner cases. Fix location tracking after a 0x2028 or 0x2029 character in a string literal (which before did not increase the line number). Fix an issue where arrow function bodies in for loop context would inappropriately consume `in` operators. Fix wrong end locations stored on SequenceExpression nodes. Implement restriction that `for`/`of` loop LHS can't start with `let`. ### New features Add support for ES2022 class static blocks. Allow multiple input files to be passed to the CLI tool. ## 8.4.1 (2021-06-24) ### Bug fixes Fix a bug where `allowAwaitOutsideFunction` would allow `await` in class field initializers, and setting `ecmaVersion` to 13 or higher would allow top-level await in non-module sources. ## 8.4.0 (2021-06-11) ### New features A new option, `allowSuperOutsideMethod`, can be used to suppress the error when `super` is used in the wrong context. ## 8.3.0 (2021-05-31) ### New features Default `allowAwaitOutsideFunction` to true for ECMAScript 2022 an higher. Add support for the `d` ([indices](https://github.com/tc39/proposal-regexp-match-indices)) regexp flag. ## 8.2.4 (2021-05-04) ### Bug fixes Fix spec conformity in corner case 'for await (async of ...)'. ## 8.2.3 (2021-05-04) ### Bug fixes Fix an issue where the library couldn't parse 'for (async of ...)'. Fix a bug in UTF-16 decoding that would read characters incorrectly in some circumstances. ## 8.2.2 (2021-04-29) ### Bug fixes Fix a bug where a class field initialized to an async arrow function wouldn't allow await inside it. Same issue existed for generator arrow functions with yield. ## 8.2.1 (2021-04-24) ### Bug fixes Fix a regression introduced in 8.2.0 where static or async class methods with keyword names fail to parse. ## 8.2.0 (2021-04-24) ### New features Add support for ES2022 class fields and private methods. ## 8.1.1 (2021-04-12) ### Various Stop shipping source maps in the NPM package. ## 8.1.0 (2021-03-09) ### Bug fixes Fix a spurious error in nested destructuring arrays. ### New features Expose `allowAwaitOutsideFunction` in CLI interface. Make `allowImportExportAnywhere` also apply to `import.meta`. ## 8.0.5 (2021-01-25) ### Bug fixes Adjust package.json to work with Node 12.16.0 and 13.0-13.6. ## 8.0.4 (2020-10-05) ### Bug fixes Make `await x ** y` an error, following the spec. Fix potentially exponential regular expression. ## 8.0.3 (2020-10-02) ### Bug fixes Fix a wasteful loop during `Parser` creation when setting `ecmaVersion` to `"latest"`. ## 8.0.2 (2020-09-30) ### Bug fixes Make the TypeScript types reflect the current allowed values for `ecmaVersion`. Fix another regexp/division tokenizer issue. ## 8.0.1 (2020-08-12) ### Bug fixes Provide the correct value in the `version` export. ## 8.0.0 (2020-08-12) ### Bug fixes Disallow expressions like `(a = b) = c`. Make non-octal escape sequences a syntax error in strict mode. ### New features The package can now be loaded directly as an ECMAScript module in node 13+. Update to the set of Unicode properties from ES2021. ### Breaking changes The `ecmaVersion` option is now required. For the moment, omitting it will still work with a warning, but that will change in a future release. Some changes to method signatures that may be used by plugins. ## 7.4.0 (2020-08-03) ### New features Add support for logical assignment operators. Add support for numeric separators. ## 7.3.1 (2020-06-11) ### Bug fixes Make the string in the `version` export match the actual library version. ## 7.3.0 (2020-06-11) ### Bug fixes Fix a bug that caused parsing of object patterns with a property named `set` that had a default value to fail. ### New features Add support for optional chaining (`?.`). ## 7.2.0 (2020-05-09) ### Bug fixes Fix precedence issue in parsing of async arrow functions. ### New features Add support for nullish coalescing. Add support for `import.meta`. Support `export * as ...` syntax. Upgrade to Unicode 13. ## 6.4.1 (2020-03-09) ### Bug fixes More carefully check for valid UTF16 surrogate pairs in regexp validator. ## 7.1.1 (2020-03-01) ### Bug fixes Treat `\8` and `\9` as invalid escapes in template strings. Allow unicode escapes in property names that are keywords. Don't error on an exponential operator expression as argument to `await`. More carefully check for valid UTF16 surrogate pairs in regexp validator. ## 7.1.0 (2019-09-24) ### Bug fixes Disallow trailing object literal commas when ecmaVersion is less than 5. ### New features Add a static `acorn` property to the `Parser` class that contains the entire module interface, to allow plugins to access the instance of the library that they are acting on. ## 7.0.0 (2019-08-13) ### Breaking changes Changes the node format for dynamic imports to use the `ImportExpression` node type, as defined in [ESTree](https://github.com/estree/estree/blob/master/es2020.md#importexpression). Makes 10 (ES2019) the default value for the `ecmaVersion` option. ## 6.3.0 (2019-08-12) ### New features `sourceType: "module"` can now be used even when `ecmaVersion` is less than 6, to parse module-style code that otherwise conforms to an older standard. ## 6.2.1 (2019-07-21) ### Bug fixes Fix bug causing Acorn to treat some characters as identifier characters that shouldn't be treated as such. Fix issue where setting the `allowReserved` option to `"never"` allowed reserved words in some circumstances. ## 6.2.0 (2019-07-04) ### Bug fixes Improve valid assignment checking in `for`/`in` and `for`/`of` loops. Disallow binding `let` in patterns. ### New features Support bigint syntax with `ecmaVersion` >= 11. Support dynamic `import` syntax with `ecmaVersion` >= 11. Upgrade to Unicode version 12. ## 6.1.1 (2019-02-27) ### Bug fixes Fix bug that caused parsing default exports of with names to fail. ## 6.1.0 (2019-02-08) ### Bug fixes Fix scope checking when redefining a `var` as a lexical binding. ### New features Split up `parseSubscripts` to use an internal `parseSubscript` method to make it easier to extend with plugins. ## 6.0.7 (2019-02-04) ### Bug fixes Check that exported bindings are defined. Don't treat `\u180e` as a whitespace character. Check for duplicate parameter names in methods. Don't allow shorthand properties when they are generators or async methods. Forbid binding `await` in async arrow function's parameter list. ## 6.0.6 (2019-01-30) ### Bug fixes The content of class declarations and expressions is now always parsed in strict mode. Don't allow `let` or `const` to bind the variable name `let`. Treat class declarations as lexical. Don't allow a generator function declaration as the sole body of an `if` or `else`. Ignore `"use strict"` when after an empty statement. Allow string line continuations with special line terminator characters. Treat `for` bodies as part of the `for` scope when checking for conflicting bindings. Fix bug with parsing `yield` in a `for` loop initializer. Implement special cases around scope checking for functions. ## 6.0.5 (2019-01-02) ### Bug fixes Fix TypeScript type for `Parser.extend` and add `allowAwaitOutsideFunction` to options type. Don't treat `let` as a keyword when the next token is `{` on the next line. Fix bug that broke checking for parentheses around an object pattern in a destructuring assignment when `preserveParens` was on. ## 6.0.4 (2018-11-05) ### Bug fixes Further improvements to tokenizing regular expressions in corner cases. ## 6.0.3 (2018-11-04) ### Bug fixes Fix bug in tokenizing an expression-less return followed by a function followed by a regular expression. Remove stray symlink in the package tarball. ## 6.0.2 (2018-09-26) ### Bug fixes Fix bug where default expressions could fail to parse inside an object destructuring assignment expression. ## 6.0.1 (2018-09-14) ### Bug fixes Fix wrong value in `version` export. ## 6.0.0 (2018-09-14) ### Bug fixes Better handle variable-redefinition checks for catch bindings and functions directly under if statements. Forbid `new.target` in top-level arrow functions. Fix issue with parsing a regexp after `yield` in some contexts. ### New features The package now comes with TypeScript definitions. ### Breaking changes The default value of the `ecmaVersion` option is now 9 (2018). Plugins work differently, and will have to be rewritten to work with this version. The loose parser and walker have been moved into separate packages (`acorn-loose` and `acorn-walk`). ## 5.7.3 (2018-09-10) ### Bug fixes Fix failure to tokenize regexps after expressions like `x.of`. Better error message for unterminated template literals. ## 5.7.2 (2018-08-24) ### Bug fixes 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. ## 5.7.0 (2018-06-15) ### New features Upgraded to Unicode 11. ## 5.6.0 (2018-05-31) ### New features 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`. ## 5.5.3 (2018-03-08) ### Bug fixes A _second_ republish of the code in 5.5.1, this time with yarn, to hopefully get valid timestamps. ## 5.5.2 (2018-03-08) ### Bug fixes 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. ## 5.5.1 (2018-03-06) ### Bug fixes Fix misleading error message for octal escapes in template strings. ## 5.5.0 (2018-02-27) ### New features 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 (2018-02-01) ### Bug fixes Disallow duplicate or escaped flags on regular expressions. Disallow octal escapes in strings in strict mode. ### New features Add support for async iteration. Add support for object spread and rest. ## 5.3.0 (2017-12-28) ### Bug fixes 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. ### New features Parsing class members was factored into smaller methods to allow plugins to hook into it. ## 5.2.1 (2017-10-30) ### Bug fixes Fix a token context corruption bug. ## 5.2.0 (2017-10-30) ### Bug fixes Fix token context tracking for `class` and `function` in property-name position. Make sure `%*` isn't parsed as a valid operator. Allow shorthand properties `get` and `set` to be followed by default values. Disallow `super` when not in callee or object position. ### New features Support [`directive` property](https://github.com/estree/estree/compare/b3de58c9997504d6fba04b72f76e6dd1619ee4eb...1da8e603237144f44710360f8feb7a9977e905e0) on directive expression statements. ## 5.1.2 (2017-09-04) ### Bug fixes Disable parsing of legacy HTML-style comments in modules. Fix parsing of async methods whose names are keywords. ## 5.1.1 (2017-07-06) ### Bug fixes Fix problem with disambiguating regexp and division after a class. ## 5.1.0 (2017-07-05) ### Bug fixes Fix tokenizing of regexps in an object-desctructuring `for`/`of` loop and after `yield`. Parse zero-prefixed numbers with non-octal digits as decimal. Allow object/array patterns in rest parameters. Don't error when `yield` is used as a property name. Allow `async` as a shorthand object property. ### New features Implement the [template literal revision proposal](https://github.com/tc39/proposal-template-literal-revision) for ES9. ## 5.0.3 (2017-04-01) ### Bug fixes Fix spurious duplicate variable definition errors for named functions. ## 5.0.2 (2017-03-30) ### Bug fixes A binary operator after a parenthesized arrow expression is no longer incorrectly treated as an error. ## 5.0.0 (2017-03-28) ### Bug fixes Raise an error for duplicated lexical bindings. Fix spurious error when an assignement expression occurred after a spread expression. Accept regular expressions after `of` (in `for`/`of`), `yield` (in a generator), and braced arrow functions. Allow labels in front or `var` declarations, even in strict mode. ### Breaking changes Parse declarations following `export default` as declaration nodes, not expressions. This means that class and function declarations nodes can now have `null` as their `id`. ## 4.0.11 (2017-02-07) ### Bug fixes Allow all forms of member expressions to be parenthesized as lvalue. ## 4.0.10 (2017-02-07) ### Bug fixes Don't expect semicolons after default-exported functions or classes, even when they are expressions. Check for use of `'use strict'` directives in non-simple parameter functions, even when already in strict mode. ## 4.0.9 (2017-02-06) ### Bug fixes Fix incorrect error raised for parenthesized simple assignment targets, so that `(x) = 1` parses again. ## 4.0.8 (2017-02-03) ### Bug fixes Solve spurious parenthesized pattern errors by temporarily erring on the side of accepting programs that our delayed errors don't handle correctly yet. ## 4.0.7 (2017-02-02) ### Bug fixes Accept invalidly rejected code like `(x).y = 2` again. Don't raise an error when a function _inside_ strict code has a non-simple parameter list. ## 4.0.6 (2017-02-02) ### Bug fixes Fix exponential behavior (manifesting itself as a complete hang for even relatively small source files) introduced by the new 'use strict' check. ## 4.0.5 (2017-02-02) ### Bug fixes Disallow parenthesized pattern expressions. Allow keywords as export names. Don't allow the `async` keyword to be parenthesized. Properly raise an error when a keyword contains a character escape. Allow `"use strict"` to appear after other string literal expressions. Disallow labeled declarations. ## 4.0.4 (2016-12-19) ### Bug fixes Fix crash when `export` was followed by a keyword that can't be exported. ## 4.0.3 (2016-08-16) ### Bug fixes Allow regular function declarations inside single-statement `if` branches in loose mode. Forbid them entirely in strict mode. Properly parse properties named `async` in ES2017 mode. Fix bug where reserved words were broken in ES2017 mode. ## 4.0.2 (2016-08-11) ### Bug fixes Don't ignore period or 'e' characters after octal numbers. Fix broken parsing for call expressions in default parameter values of arrow functions. ## 4.0.1 (2016-08-08) ### Bug fixes Fix false positives in duplicated export name errors. ## 4.0.0 (2016-08-07) ### Breaking changes The default `ecmaVersion` option value is now 7. A number of internal method signatures changed, so plugins might need to be updated. ### Bug fixes The parser now raises errors on duplicated export names. `arguments` and `eval` can now be used in shorthand properties. Duplicate parameter names in non-simple argument lists now always produce an error. ### New features The `ecmaVersion` option now also accepts year-style version numbers (2015, etc). Support for `async`/`await` syntax when `ecmaVersion` is >= 8. Support for trailing commas in call expressions when `ecmaVersion` is >= 8. ## 3.3.0 (2016-07-25) ### Bug fixes Fix bug in tokenizing of regexp operator after a function declaration. Fix parser crash when parsing an array pattern with a hole. ### New features Implement check against complex argument lists in functions that enable strict mode in ES7. ## 3.2.0 (2016-06-07) ### Bug fixes Improve handling of lack of unicode regexp support in host environment. Properly reject shorthand properties whose name is a keyword. ### New features Visitors created with `visit.make` now have their base as _prototype_, rather than copying properties into a fresh object. ## 3.1.0 (2016-04-18) ### Bug fixes Properly tokenize the division operator directly after a function expression. Allow trailing comma in destructuring arrays. ## 3.0.4 (2016-02-25) ### Fixes Allow update expressions as left-hand-side of the ES7 exponential operator. ## 3.0.2 (2016-02-10) ### Fixes Fix bug that accidentally made `undefined` a reserved word when parsing ES7. ## 3.0.0 (2016-02-10) ### Breaking changes The default value of the `ecmaVersion` option is now 6 (used to be 5). Support for comprehension syntax (which was dropped from the draft spec) has been removed. ### Fixes `let` and `yield` are now “contextual keywords”, meaning you can mostly use them as identifiers in ES5 non-strict code. A parenthesized class or function expression after `export default` is now parsed correctly. ### New features When `ecmaVersion` is set to 7, Acorn will parse the exponentiation operator (`**`). The identifier character ranges are now based on Unicode 8.0.0. Plugins can now override the `raiseRecoverable` method to override the way non-critical errors are handled. ## 2.7.0 (2016-01-04) ### Fixes Stop allowing rest parameters in setters. Disallow `y` rexexp flag in ES5. Disallow `\00` and `\000` escapes in strict mode. Raise an error when an import name is a reserved word. ## 2.6.2 (2015-11-10) ### Fixes Don't crash when no options object is passed. ## 2.6.0 (2015-11-09) ### Fixes Add `await` as a reserved word in module sources. Disallow `yield` in a parameter default value for a generator. Forbid using a comma after a rest pattern in an array destructuring. ### New features Support parsing stdin in command-line tool. ## 2.5.0 (2015-10-27) ### Fixes Fix tokenizer support in the command-line tool. Stop allowing `new.target` outside of functions. Remove legacy `guard` and `guardedHandler` properties from try nodes. Stop allowing multiple `__proto__` properties on an object literal in strict mode. Don't allow rest parameters to be non-identifier patterns. Check for duplicate paramter names in arrow functions.