# Releases & change log

This document chronicles quick-lint-js' releases. This document's format is based on Keep a Changelog.

quick-lint-js' version numbers are arbitrary. quick-lint-js does not adhere to Semantic Versioning.

## 2.19.0 (2023-12-30)

Downloads

### Added

- Unicode 15.1 is now supported, including new CJK code points in identifiers.
- Missing `break;` (or `return;` or `throw ...;` or `// fallthrough`) after a clause in `switch` statement now reports E0427 ("missing 'break;' or '// fallthrough' comment between statement and 'case'"). (Implemented by Yash Masani.)
- Detection of multiple `export default` statements (E0715) now also applies to `export {... as default};` statements.
- JSX elements and fragments are now allowed in JSX attributes without surrounding them in `{` and `}` (e.g. `<List header=<ListHeader />>{items}</List>`).
- TypeScript support (still experimental):
  - `export as namespace` statements are now parsed.
  - Const generic parameters (`<const T>`) are now parsed.
  - Assertion signatures (`function f(param): asserts param`) are now parsed.
  - If a type predicate appears outside a return type, quick-lint-js now reports E0426 ("type predicates are only allowed as function return types").
  - `export default` now supports separately-declared TypeScript interfaces and types.
  - `cond ? (param): ReturnType => body : f` is now correctly parsed as a conditional expression with a function in the truthy branch. (`cond ? (t) : param => body` continues to be parsed as a conditional expression with a function in the falsy branch.)
  - Using `<<` in an interface's `extends` clause, in a class's `implements` clause, or in a `typeof` type now reports E0429 instead of misleading diagnostics. (Implemented by strager and Ariel Don.)
  - Properties in object literal types can now be named with number and string literals.
  - Repeating `in` or `out` generic parameter modifiers now reports [E0432][] ("'in' or 'out' variance specifier cannot be listed twice").
  - Writing a newline after an `in`, `out`, or `const` generic parameter modifier now reports [E0440][] ("newline is not allowed after 'in' modifier in generic parameter"). (Implemented by Ariel Don.)
  - Negative number literals are now parsed in types.
  - Parameter decorators are now parsed.
  - Overload signatures are now allowed on exported functions.
  - Assigning to a class now reports E0003 ("cannot assign to class").
  - Definite assignment assertions (`!` after a variable name in `let` or `var`) is now supported.
  - `override` is now supported in classes.
  - Abstract constructor types (such as `abstract new () => C`) are now supported.
  - `export class { m(); }` in a .d.ts file no longer falsely reports [E0172][] ("missing body for function").
  - `import()` type assertions are now allowed in TypeScript types.
  - U+0085 (Next Line) is now interpreted as whitespace.

### Fixed

- Class decorators may now reference the class by name.
- Decorators are now parsed correctly when using a semicolon-free coding style.
- Properties named 'private', 'declare', or similar names are now parsed correctly when using a semicolon-free coding style.
- A newline between an arrow function and a parenthesized expression (e.g. `let f = () => {} /*newline*/ (console.log('x'));` no longer falsely reports E0211 ("missing parentheses around self-invoked function").
- `for await (async of []);` no longer falsely reports [E0082][] ("assigning to 'async' in a for-of loop requires parentheses"). (`for (async of []);` still reports the diagnostic.)
- A `return` statement inside a nested `switch` no longer falsely repots E0427 ("missing 'break;' or '// fallthrough' comment between " "statement and 'case'").
- TypeScript support (still experimental):
  - Types named `await`, `implements`, `interface`, `let`, `package`, `private`, `protected`, `public`, `static`, and `yield` are now recognized in type signatures.
  - `export default` with a class and an interface (triggering declaration merging) no longer fasely reports E0715 ("cannot use multiple `export default` statements in one module").
  - `class C<T extends U, U> {}` no longer falsely reports E0058 ("variable used before declaration").
  - `case await x:` no longer treats `:` as if it was a type annotation colon in an arrow function parameter list.
  - Fixed a crash if certain diagnostics are reported after a TypeScript interface. (Implemented by Rui Serra.)
  - `import("modulename").Class<<T>(params) => ReturnType>` in a type is now parsed correctly.
  - `import("modulename")` in a type is now allowed and no longer falsely reports a diagnostic.
  - `import type * from 'othermodule';` no longer crashes quick-lint-js with an assertion failure.
  - Generic call signatures are now parsed correctly when using a semicolon-free coding style.
  - Interface index signatures and computed property names in interfaces are now parsed correctly when using a semicolon-free coding style.
  - Properties named 'extends' or 'is' are now parsed correctly when using a semicolon-free coding style.
  - Types named 'asserts' are parsed correctly when using a semicolon-free coding style.
  - `declare const x = 42;` no longer falsely reports [E0351][] or [E0385][].
  - `type T = T.thing;` no longer falsely reports E0384 ("cannot use type directly in its own definition").
  - Interface methods and index signatures can now end in `,` (in addition to `;`).
  - Parsing of `;` and `,` between and after properties in object types is much less buggy.
  - quick-lint-js no longer incorrectly reports E0384 ("cannot use type directly in its own definition") when using `extends ? :`.
  - Making a type alias and a function with the same name no longer falsely reports E0034 ("redeclaration of variable").
  - Importing a type then declaring a function or variable with the same name no longer falsely reports E0034 ("redeclaration of variable").
  - Importing a function or variable then declaring a type with the same name no longer falsely reports E0034 ("redeclaration of variable").
  - `T extends () => RT ? A : B` no longer falsely reports E0348 ("unexpected '?' in type; use '| void' to make an optional type").
  - `<T extends />` is now correctly parsed as a JSX element.
  - `interface I { get: any; }` (field named `get` with a type annotation) no longer reports E0054 ("unexpected token"). (Implemented by Rui Serra.)
  - In type assertions, certain types such as in `<string[]>expr` and `< <T>() => RT>expr`, are no longer incorrectly interpreted as JSX.
  - Assigning to an enum or namespace no longer crashes quick-lint-js with an assertion failure.
  - Subnamespaces can now be named contextual keywords such as `string`.
  - Import aliases can now be named contextual keywords such as `implements`.
  - Optional function parameters can now be named contextual keywords such as `readonly`.
  - Import aliases can now be declared with `import type`.
  - Namespace aliases can now reference variables named contextual keywords such as `yield` inside namespaces.
  - Type annotations can now reference types inside namespaces named contextual keywords such as `string`.
  - `import A = ns; class A {}` no longer crashes or falsely reports that `A` was redeclared.
  - `import {type A from 'mod'}; let A;` no longer crashes or falsely reports that `A` was redeclared.
  - `extends` checks with multiple `infer`s no longer crash or falsely report that the inferred variable was redeclared.
  - `class implements I {}` is now parsed as a class with no name rather than a class with the name `implements`.
  - `class C extends Base<T> implements I {}` now correctly parses `Base<T>` as a type with generic arguments rather than logical comparisons.
  - Variables declared inside a `declare global` block are now correctly declared as global variables instead of module variables. This means that variables inside a `declare global` block can be shadowed by module variables without diagnostics.
  - Fixed false negatives for E0196 if a type has the same name as a variable.
  - Using a variable in a type or interface (e.g. with `typeof`) no longer falsely reports E0058 ("variable used before declaration").
  - Type predicates in function types no longer falsely report [E0315][] ("'param' is not the name of a parameter").
  - Arrow functions with return type annotations such as `(42)` or `(string[])` are now parsed correctly.
  - `f<T>?.()` (optional chaining function call with generic function arguments) is now parsed correctly.
  - In a .d.ts file, `declare module` without a body no longer falsely reports errors.
  - `export default` inside a `declare module` no longer falsely reports E0715 ("cannot use multiple `export default` statements in one module").
  - `typeof` in types now supports variables named `boolean`, `string`, and some other names.
  - An optional parameter with `?` followed by an optional parameter with `=` no longer falsely reports E0379 ("optional parameter cannot be followed by a required parameter").
  - `extends` in some cases is no longer incorrectly interpreted as an `infer` constraint, such as in `MyType extends (infer T extends U ? T1 : F1) ? T2 : F2;`.
  - Nested `extends`, such as in `A extends () => B extends C ? D : E ? F : G`, no longer falsely reports E0348 ("unexpected '?' in type; use '| void' to make an optional type").
  - `class T<T> {}` no longer falsely reports E0034 ("redeclaration of variable").
  - `await <T>() => {}` no longer does confusing things.

## 2.18.0 (2023-11-03)

Downloads

### Added

- Mixing `&` and `<<` such as in `a & 0x1 << 3` now reports E0716 ("unintuitive operator precedence when using & and << or >>"). (Implemented by toastin0.)

### Fixed

- A missing operator in an `if` condition (such as in `if (x y)`) no longer causes E0065 ("'else' has no corresponding 'if'") to be reported. (Implemented by Ariel Don.)
- `cmake --install` with `--component build-tools` now installs the build tools. (This is a regression introduced in quick-lint-js version 2.16.0.)
- Windows: The installer and executables are now signed with a non-expired certificate chain.

## 2.17.0 (2023-10-25)

Downloads

### Known issues

- `cmake --install` with `--component build-tools` does not install the build tools. (This is a regression introduced in quick-lint-js version 2.16.0.) Fix: Git commit 3923f0df76d24b73d57f15eec61ab190ea048093
- Windows: Code signing does not validate on some machines. Workaround: follow SSL.com's instructions for removing the expired "Certum Trusted Network CA" certificate.

### Added

- quick-lint-js now understands decorators.
- quick-lint-js now understands `accessor` fields.
- `class C { myField, }` now reports better diagnostics.
- quick-lint-js now compiles correctly on big-endian architectures such as S/390 (Linux s390x).
- Missing commas in array literals now reports E0712. (Implemented by koopiehoop.)
- `get *prop()` and `set *prop()` in classes now report E0713 ("getters and setters cannot be generators"). (Implemented by koopiehoop.)
- `async get` and `async set` in classes now report E0714 ("'async' keyword is not allowed on getters or setters"). (Implemented by koopiehoop.)
- Multiple `export default` statements now report E0715 ("cannot use multiple `export default` statements in one module"). (Implemented by Ariel Don.)
- Emacs: The Debian/Ubuntu package now installs the Emacs plugin. Manual installation of the .el files is no longer required.
- CLI: The new `--stdin-path` CLI option allows users of the `--stdin` option (primarily text editors) to have quick-lint-js detect the language automatically via `--language=default` or `--language=experimental-default`.
- TypeScript support (still experimental):
  - CLI: The new `--language=experimental-default` option auto-detects the language based on the file's extension (`.ts`, `.tsx`, `.d.ts`, or `.js`).
  - Emacs: Flymake plugin users can now opt into TypeScript support. See the Flymake configuration instructions.
  - Class method overload signatures are now parsed.
  - E0398 is now reported when using both `abstract` and `static` on a single class property.
  - `,` is now allowed after interface fields. (Previously only `;` or a newline was allowed.)
  - `if (cond);` now reports E0064 ("missing body for 'if' statement"). (Implemented by Samir Hamud.)
  - Type predicates are now supported in function types (e.g. `(param) => param is Type`).
  - `declare` fields are now parsed inside classes.
  - `declare global` blocks are now parsed.

### Fixed

- E0072 is no longer falsely reported if `function` has a newline after it.
- E0196 is no longer falsely reported if the shadowing variable is declared in the head of a `for` loop. For example, quick-lint-js no longer warns about `let x; for (let x = 0;;);`.
- Emacs: .el files are now installed in the correct place on Arch Linux, btw.
- Emacs: The Flymake plugin now reliably clears out diagnostics after issues are fixed. Sticky diagnostics are no more.
- TypeScript support (still experimental):
  - A newline after `public`, `protected`, `private`, or `readonly` inside a class is now interpreted correctly.
  - `<T>(T: T) => {}` (a generic arrow function with the same name for a run-time parameter and a generic parameter) no longer falsely reports E0034 ("redeclaration of variable").
  - A namespace with the same name as an interface or type alias no longer falsely reports E0034 ("redeclaration of variable").
  - `declare class` and `function` with the same name no longer falsely reports E0034 ("redeclaration of variable").
  - `(a?, ...b) => ReturnType` in a TypeScript type no longer falsely reports E0379 ("optional parameter cannot be followed by a required parameter").
  - LSP: A file named `a.tsxbanana.ts` is no longer recognized as a TypeScript JSX file. It is now recognized as a non-JSX TypeScript file.
  - Nested `module` declarations no longer falsely report E0361. E0361's message has been changed:
    - Before: "module with string name is only allowed at the top level"
    - After: "TypeScript 'declare module' with string name is not allowed in namespaces"

## 2.16.0 (2023-09-06)

Downloads

### Known issues

- `cmake --install` with `--component build-tools` does not install the build tools. Fix: Git commit 3923f0df76d24b73d57f15eec61ab190ea048093

### Added

- `2 ^ 8` now reports E0710 ("'^' is the XOR operator; to exponentiate, use '**' instead"). (Implemented by pedrobl1718.)
- A missing `}` in a function parameter list now reports E0161 ("unclosed object literal; expected '}'"). (Implemented by Yash Masani.)
- quick-lint-js now builds on Alpine Linux and other musl-based distributions.
- TypeScript support (still experimental):
  - Invalid recursive type definitions such as `type T = T;` now report E0384 ("cannot use type directly in its own definition").
  - quick-lint-js now recognizes `import` types.
  - quick-lint-js now recognizes `.d.ts` files:
    - CLI: `--language=experimental-typescript-definition`
    - LSP server: `typescriptdefinition`; `typescript` will detect from the URI, and `typescriptsource` prevents detection from the URI
    - Visual Studio Code extension: detected from the file name

### Fixed

- LSP: On macOS, quick-lint-js no longer hangs if a file has too many diagnostics.
- `#property in object` expressions are now parsed correctly and do not report E0155.
- `({k = defaultValue} = o);` no longer incorrectly reports E0253 ("use ':' instead of '=' in object literals").
- Class property initializers no longer incorrectly report E0058 ("variable used before declaration"). Example: `class C { myProperty = f(); } const f = () => {};`
- TypeScript support (still experimental):
  - quick-lint-js no longer falsely reports E0058 ("variable used before declaration") for code such as `function f<T extends T[]>() {}`.
  - Declaring a type alias or an interface inside a `declare namespace` no longer reports E0357 ("'declare namespace' cannot contain statements, only declarations").
  - `const enum E {}` no longer causes E0150.
  - Using a `declare`-ed variable prior to its declaration is now allowed. Example: `new C(); declare class C { }`
  - Using a variable in a `declare class`'s `extends` clause prior to the variable's declaration is now allowed. Example: `declare class Derived extends Base { } class Base { }`
  - VS Code: The extension now loads when only opening a TypeScript file. (Previously, the extension would only load when you opened a JavaScript or JSON file.) The `quick-lint-js.experimental-typescript` setting is still required.
  - Vim ALE: JSX syntax is now recognized inside `.tsx` files.

### Changed

- quick-lint-js no longer depends on the Boost third-party library. The `QUICK_LINT_JS_USE_BUNDLED_BOOST` CMake variable now has no effect.

## 2.15.0 (2023-07-18)

Downloads

### Added

- LSP server: quick-lint-js can now receive configuration options via the `initialize` request. See LSP configuration documentation for details.
- `x = x;` now reports E0383. (Implemented by Austin Garcia.)
- `...` without something following it now reports either E0708 ("unexpected '...'; expected expression") or E0709 ("expected variable name after '...'"). (Implemented by Isaac Nonato.)
- TypeScript support (still experimental):
  - `namespace A.B {}` syntax (with `.`) is now supported.
  - `static public myMethod() {}` now reports E0380 ("'public' access specifier must precede 'static'"). (Implemented by Leszek Nowicki.)
  - `class C { \u{63}onstructor() {} }` now reports E0381 ("Typescript does not allow keywords to contain escape sequence"). (Implemented by Jait Jacob.)
  - `export declare` is now supported.

### Fixed

- Emacs (Flycheck): Using `C-x C-;` to comment a line now runs quick-lint-js (instead of leaving old diagnostics on the screen). This requires that you update your Emacs file: add `new-line` to the `flycheck-check-syntax-automatically` variable.
- `export default abstract;` is now parsed correctly as the export of a variable named `abstract`.
- `export default async (newline) function f() {}` is now parsed correctly as the export of a variable named `async` followed by the declaration of a non-async function named `f`.
- TypeScript support (still experimental):
  - E0034 ("redeclaration of variable") is no longer incorrectly reported in various cases, including the following:
    - `class A {} namespace A {}`
    - `function f<T>(T) {}`
    - `type X = null; var X;`
    - `namespace ns{} namespace ns{}`
  - `export = a b` now reports E0027 ("missing semicolon after statement").
  - `module 'name' { import ... }` no longer falsely reports E0362 ("cannot import a module from inside a 'declare namespace'").
  - `module 'name';` no longer falsely reports E0356 ("missing body for TypeScript namespace").

## 2.14.0 (2023-05-22)

Downloads

### Added

- Missing props in JSX tags now report E0376 ("JSX prop is missing an expression"). (Implemented by James Moles.)
- `! ==` (with a space) now reports E0373 or E0374. (Implemented by daethtech.)
- `x == y ?? true` now reports E0369. (Implemented by Kate Conkright.)
- `apt install quick-lint-js` now works on ARM64 (AArch64) Debian and Ubuntu installations.
- TypeScript support (still experimental):
  - Certain invalid parameter properties (such as in `constructor(public {id, name})`) now report diagnostics.
  - `function f(a?, b) {}` now reports E0379. (Implemented by Alek Lefebvre.)

### Fixed

- Arrow functions with TypeScript parameter type annotations no longer report confusing diagnostics in JavaScript mode. (Implemented by Leszek Nowicki.)
- TypeScript support (still experimental):
  - '`hello${world}` as const' no longer falsely reports E0291. (Fixed by Leszek Nowicki.)
- Windows: Fixed a build failure with MinGW GCC 13.1.0.
- Shell completions are now up to date with the CLI. (Fixed by Jake Castelli.)
- FreeBSD: quick-lint-js no longer fails to build.

### Changed

- Ubuntu 18.04 LTS Bionic is no longer supported. It might happen to work, but it is not extensively tested. Canonical is itself ending support for Bionic on May 31, 2023, so please upgrade to Ubuntu 20.04 LTS or newer.

## 2.13.0 (2023-04-13)

Downloads

### Known issues

- Building quick-lint-js on FreeBSD is broken.

### Added

- quick-lint-js now recognizes Deno's global variables, including `Deno`. This suppresses undesired E0057 ("use of undeclared variable") warnings. This is controlled by the `deno` global group.
- `if () {}` (without a condition) now reports E0452 ("empty parenthesis after control statement"). (Implemented by Yunus.)
- `return x,` now reports E0026 ("missing operand for operator"). (Implemented by Tom Binford.)
- TypeScript support (still experimental):
  - The `satisfies` operator is now recognized.
  - The `infer` operator is now recognized.
  - The `in` and `out` keywords for generic parameter variance are now recognized.
  - Parameter properties (`constructor(public readonly name: string, public age: number)`) are now recognized.
  - `C<T>=y;` now reports E0365 ("TypeScript requires whitespace between '>' and '=' here").
  - `extends` in `interface` now allows generic arguments, such as in `interface I extends T<U> {}`.
  - `extends` in `interface` now allows nested namespaces, such as in `interface I extends ns1.ns2.ns3.I {}`.
- FreeBSD: `quick-lint-js --debug-apps` now works. (Implemented by Nico Sonack.)

### Fixed

- Fixed several false errors:
  - `do while (x); while (y);` no longer falsely reports E0101 ("missing body for do-while loop").
  - `{ var async; async }` no longer falsely reports E0054 ("unexpected token").
  - `async[x]` no longer falsely reports E0054 ("unexpected token").
  - `await x ? y : z` no longer falsely reports E0311 ("missing parentheses around parameter").
  - `if (c) async () => {}; else {}` no longer falsely reports E0065 ("'else' has no corresponding 'if'").
  - `class A extends await {}` no longer falsely reports E0111 ("missing body for class").
  - `class A extends await() {}` no longer falsely reports E0176 ("missing arrow operator for arrow function").
  - `do if (c) {} else (b); while (d);` no longer falsely reports E0103 ("missing 'while (condition)' for do-while statement").
- `if (c) {} else (b) d;` now correctly reports E0027 ("missing semicolon after statement").
- The CLI's `--output-format=gnu-like` output (default) no longer prints terminal escape sequences for "dumb" terminals (where `TERM=dumb`). (Fixed by wagner riffel.)
- FreeBSD: The quick-lint-js-licenses.txt file is now populated correctly.
- TypeScript support (still experimental):
  - `let x: C<T>=y;` no longer falsely reports an error.
  - `class A extends B<C> {}` no longer falsely reports an error.
  - `T extends keyof O ? A : B` no longer falsely reports an error.

### Changed

- Cross compiling now requires you to build with `QUICK_LINT_JS_ENABLE_BUILD_TOOLS` for the build machine then with `QUICK_LINT_JS_USE_BUILD_TOOLS` for the target machine. See the cross-compiling documentation for details.
- Code signing certificate has been refreshed. The old certificate expires on April 18, 2023 (PDT) and the new certificate expires on April 17, 2024 (PDT). The public key is the same between the two certificates: `7ea531a42cd3e7161b6951f93d83449546e90722` (SHA1).

## 2.12.0 (2023-03-08)

Downloads

### Added

- `array[i, j]` now reports E0450 ("misleading use of ',' operator in index") (implemented by Yunus).
- `while (x > 0, y > 0)` now reports E0451 ("misleading use of ',' operator in conditional statement") (implemented by Yunus).
- Improvements to experimental TypeScript support:
  - Type variables such as `Readonly<T>` and `IArguments` are now recognized by the new `typescript` global group which is enabled by default.
  - `declare` is now supported.
  - The old-style `module` syntax for namespaces is now supported.

### Fixed

- Fixed E0062 being reported when E0061 should be reported instead (fixed by Yunus).
- TypeScript `namespace` without a body now reports E0356 instead of crashing with an assertion failure.

### Changed

- quick-lint-js' build system now optionally creates executes and runs them during the build. This behavior is controlled by the `QUICK_LINT_JS_ENABLE_BUILD_TOOLS` and `QUICK_LINT_JS_USE_BUILD_TOOLS` CMake variables.
  - For most people, `QUICK_LINT_JS_ENABLE_BUILD_TOOLS` is enabled by default and should work without extra configuration. No action is needed.
  - When cross-compiling, `QUICK_LINT_JS_ENABLE_BUILD_TOOLS` is disabled. Currently, `QUICK_LINT_JS_ENABLE_BUILD_TOOLS` is optional, so this should behave as before. However, in the future, either `QUICK_LINT_JS_ENABLE_BUILD_TOOLS` or `QUICK_LINT_JS_USE_BUILD_TOOLS` will be required.
  - If you need to configure the build tools specially, or if you want to build the build tools when cross-compiling, you must use the `QUICK_LINT_JS_USE_BUILD_TOOLS` CMake variable. See the cross-compiling documentation for instructions on using `QUICK_LINT_JS_USE_BUILD_TOOLS` correctly.

## 2.11.0 (2023-01-31)

Downloads

### Changed

- Debian: The apt repository signing key expired on (2023-01-21). This causes `apt-get update` to fail. To fix this issue, add the latest signing key by running the following command:

      $ curl https://c.quick-lint-js.com/quick-lint-js-release.key | sudo apt-key add -

- LSP: The quick-lint-js LSP server no longer accepts JSON-RPC 2.0 batch messages. In practice, LSP clients don't use this feature, so this breaking change should do no harm. The LSP specification recently started prohibiting batch messages to match the status quo.

### Added

- LSP: The LSP server now recognizes and lints TypeScript and TypeScript JSX code. However, the editor plugins currently do not use this feature by default.
- Vim: You can opt into TypeScript support. Search for `EXPERIMENTAL` in `:help quick-lint-js`. (Disabled by default.)
- VS Code: You can now opt into experimental TypeScript support. Set the `quick-lint-js.experimental-typescript` setting to `true`. (Disabled by default.)
- `switch (c) { case A: break; case A: break; }` now reports E0347 ("duplicated case clause in switch statement") (implemented by Rebraws).
- Translations: Brazilian Portuguese (implemented by Guilherme Vasconcelos).
- Mixing up the order of the `export`, `async`, and `function` keywords now reports E0326 or E0327 (implemented by Alek Lefebvre).
- TypeScript types like `string?` now report E0348 (implemented by Alek Lefebvre).
- Extra parentheses in function parameters now report E0349 (function parameter cannot be parenthesized) (implemented by Harshit Aghera).
- QuickJS's global variables are now recognized by default via the new `quickjs` global group (implemented by wagner riffel).
- E0190 is now reported if the literal is `undefined`, not only `null`, strings, and numbers (implemented by Harshit Aghera).

### Fixed

- Variables can be named according to Unicode 15 (previously Unicode 14).
- In tracing files, the thread IDs in the file headers are now correct if tracing was enabled after startup.
- E0325 is now an error rather than a warning.
- `0o123.toString()`, `0x123.toString()`, `0b101.toString()`, and `0123.toString()` no longer incorrectly report E0046, E0047, or E0048.
- Using a variable called `async`, then exporting something, no longer reports an unexpected token error (implemented by Alek Lefebvre).
- `class C { x = 0, y; }` now reports E0330 ("',' should be ';' instead") instead of E0057 ("use of undeclared variable: y") (implemented by clegoz).

## 2.10.0 (2022-10-14)

Downloads

### Added

- E0286 and E0287 are now reported if the string or the value have extra parentheses (such as in `(tag.toUpperCase()) === 'img'`) (implemented by Rebraws).
- `myArray === []` now reports E0344 (implemented by Rebraws).
- `myArray === [a, b, c]` now reports E0341 (implemented by Rebraws).
- CLI: The new `--language` option lets you opt out of JSX support. With `--language=javascript`, quick-lint-js will report E0177 for any uses of JSX.
- You can opt into TypeScript support in the CLI using the `--language=experimental-typescript` option. TypeScript support is experimental, so there will be bugs (including crashes) in quick-lint-js. This option does not affect the LSP server.
- E0149 and E0150 are now reported for labelled statements too (implemented by Guilherme Vasconcelos).

### Fixed

- `static` code blocks in classes no longer report E0242 ("TypeScript static blocks are not supported in JavaScript").
- When writing `implements` in JavaScript code, quick-lint-js will no longer possibly report E0246 in addition to E0247. quick-lint-js will now only report E0247.
- `{ x: y = z }` in an expression no longer incorrectly reports E0253.
- `{ x: y = z }` now reports errors such as E0057 for `z`. (`z` used to be completely ignored during variable analysis.)
- `{ x = z }` now only reports E0253, instead of also reporting E0059 for `x`.
- `class C { field!; }` now only reports E0239 (TypeScript assignment-asserted fields are not supported in JavaScript) instead of both E0239 and E0236 (assignment-asserted field must have a type annotation).

### Changed

- E0707 has been merged into E0069.
- E0271 has been merged into E0270.
- E0279 has been merged into E0278.

## 2.9.0 (2022-09-05)

Downloads

### Added

- `tag.toUpperCase() === 'img'` now reports E0286, and `tag.toLowerCase() === 'IMG'` now reports E0287 (implemented by Roland Strasser).

### Fixed

- `(param) { body(); }` now reports E0176 ('missing arrow operator for arrow function') (implemented by Roland Strasser).
- quick-lint-js no longer crashes if a TypeScript `type` alias appears in a JavaScript file.
- quick-lint-js now recognizes the `jest` global variable from the Jest test framework. This suppresses undesired E0057 ("use of undeclared variable") warnings.
- `await () => x` no longer reports `x` as undeclared multiple times. (E0178 is still reported, as intended.)
- Defining a global variable in `quick-lint-js.config` which is already declared by default now always changes the `shadowable` and `writable` settings.
- `await () => await () => ...` no longer slows down linting and consumes a lot of memory.

## 2.8.0 (2022-07-25)

Downloads

### Added

- `await await f()` now reports E0266 ("redundant await") (implemented by clegoz).
- CLI: Misuse of `--vim-file-bufnr` now reports warnings (implemented by Roland Strasser).

### Fixed

- LSP, VS Code: quick-lint-js now correctly handles merging lines containing non-ASCII with lines containing ASCII. This fixes spurious diagnostics. Thanks to T0x3139 and mirabellier for reporting and helping fix this bug.
- quick-lint-js now recognizes Bun's global variables, including `Bun` and `bunJSX`. This suppresses undesired E0057 ("use of undeclared variable") warnings.

### Removed

- The `en@loud` translation has been removed. It was only used for testing.

### Changed

- Debian/Ubuntu: Our Debian/Ubuntu package now might not work on Ubuntu 16.04 or Debian 9. The following Debian-based Linux distributions are tested:
  - Debian 10 Bullseye and 11 Buster
  - PureOS Amber
  - Ubuntu 18.04 Bionic and 20.04 Focal
- Manual: Our Linux x86_64/amd64 pre-built binaries now might not work on Ubuntu 16.04 or similarly old distributions. The following Linux distributions are tested:
  - Arch Linux
  - Debian 10 Bullseye and 11 Buster
  - Fedora 35 and 36
  - Ubuntu 18.04 Bionic and 20.04 Focal

## 2.7.0 (2022-07-13)

Downloads

### Added

- `const o = {k = v};` now reports E0253 ("use ':' instead of '=' in object literals").
- `--snarky` is now even snarkier.
- LSP server: The new `quick-lint-js.tracing-directory` LSP configuration item can be set to a path where quick-lint-js will log LSP protocol traffic. This keylogger option can be used by quick-lint-js contributors to investigate bugs. This new option is disabled by default.

### Fixed

- quick-lint-js no longer fails to build with simdjson version 2.2.0.
- Declaring a TypeScript interface with the same name as a generic parameter no longer crashes quick-lint-js.

## 2.6.0 (2022-06-15)

Downloads

### Added

- `DOMError`, `MutationEvent`, and some other browser global variables are now recognized.
- New global group: `web-worker` (enabled by default)
- The `importScripts` global function is now recognized by default.
- Forgetting a semicolon between class fields now reports "missing semicolon after field" (E0223) instead of "missing semicolon after statement" (E0027).
- Using some TypeScript features, such as class generics and interfaces, in JavaScript code is now reported with a friendly error message.
- E0199 ("unclosed class") is now reported in more scenarios.
- `static` code blocks in classes are now supported.

### Fixed

- E0707 now only complains about classes named `await`, not any class inside an async function.
- E0054 is no longer incorrectly reported for class properties named `implements`, `interface`, `package`, `private`, `protected`, or `public`.
- In statement contexts, `async` followed by a newline followed by `function` is no longer falsely interpreted as an async function. It is instead interpreted as the use of a variable called `async` followed by a non-async function, per the language standard.
- `((x)) => {}` no longer crashes the parser with an assertion failure.
- Tests now pass if the user's locale is Italian (`it_IT.utf8` on Linux).
- The FreeBSD build now succeeds and tests pass.

## 2.5.0 (2022-05-23)

Downloads

### Added

- E0144 and E0145 are now reported for `implements`, `interface`, `package`, `private`, `protected`, and `public` (in addition to other keywords).
- E0086 is now reported in more cases, such as when the deleted variable was declared outside the function containing the `delete` expression.
- Classes named `await` in `async` functions now report E0707 (implemented by ooblegork).
- Integer literals which are silently rounded at run-time now report E0212 (implemented by Rob Miner).
- VS Code: The new `quick-lint-js.tracing` setting can be set to `"verbose"` to log changes to documents. This keylogger option can be used by quick-lint-js contributors to investigate bugs. This new option is disabled by default.
- CLI: The `--snarky` option makes error messages more interesting. Implemented by david doroz.

### Fixed

- E0150 no longer crashes quick-lint-js when using a German (`de`) locale. (Fixed by Nico Sonack.)
- The npm package now includes `copyright` files listing software licenses and copyright notices.
- E0086 is no longer falsely reported in some cases.
- VS Code (Windows x64): When the extension is first loaded, and a file has errors, quick-lint-js no longer reports the first error always on the first line. (The issue was a compiler bug which we worked around.)
- quick-lint-js no longer creates and writes messages to `/tmp/qljs.log`.

### Changed

- This release is signed with a new GPG key.
  - Old fingerprint: 0327DE8F9CEF499851D19F6ED20BA9DCCF0E9D20
  - New fingerprint: A6851D57A65803E98C05DA01C08A7BC89CA2F557

## 2.4.2 (2022-04-22)

Downloads

### Changed

- The name of package installed by the MSIX installer has changed. It used to be "fa6b940b-8f96-4b46-8e21-703a63133e06" but now it is "quick-lint.quick-lint-js". If you installed quick-lint-js using a prior version of the MSIX installer, Windows won't let you upgrade. Uninstall the old version of quick-lint-js before installing a new version.

## 2.4.1 (2022-04-19)

Downloads

### Fixed

- When using the `de`, `fr_FR`, or `sv_SV` locale, some error messages are no longer blank.

### Changed

- The Windows MSIX installer is now signed with a Microsoft-trusted certificate. If you installed quick-lint-js using a prior version of the MSIX installer, Windows won't let you upgrade. Uninstall the old version of quick-lint-js before installing a new version.
- The Windows executable is now signed with a Microsoft-trusted certificate.

## 2.4.0 (2022-04-15)

Downloads

### Added

- Missing parentheses around a self-invoked arrow function are now reported as E0211. (Implemented by Sarah Schulte.)
- E0179 is now reported if a JSX element such as `<div />` follows `return` (implemented by Rob Miner).

### Fixed

- `<div> <> </> </div>` (a JSX fragment inside a JSX element) no longer reports a syntax error.

### Changed

- Windows builds (x86, x64, ARM, and ARM64) are now built with MinGW's C and C++ runtime libraries instead of Microsoft's. This fixes a compliance issue with GPLv3.

## 2.3.1 (2022-03-24)

Downloads

### Added

- Windows: The 32-bit x86 builds are now code-signed.
- Windows: Tab-completion now works in PowerShell. (Completion needs to be installed manually.) (Implemented by Tony Sathre.)

### Fixed

- The executable files shared between the npm packages and the static builds are now identical. (Previously, the files sometimes differed because they were code-signed independently. Code signing is non-deterministic.)

## 2.3.0 (2022-02-24)

Downloads

### Added

- An incomplete `class` now reports E0199 instead of failing with the catch-all E0054. (Thanks to Dave Churchill for reporting.)
- Statements before the first `case` in a `switch` now report E0198 (implemented by Himanshu).
- When building from source, you can tell quick-lint-js to use your copy of third-party dependencies instead of quick-lint-js' bundled dependencies:
  - `-DQUICK_LINT_JS_USE_BUNDLED_BOOST=OFF`: Use your own copy of Boost.
  - `-DQUICK_LINT_JS_USE_BUNDLED_GOOGLE_BENCHMARK=OFF`: Use your own copy of Google Benchmark (benchmarks only).
  - `-DQUICK_LINT_JS_USE_BUNDLED_GOOGLE_TEST=OFF`: Use your own copy of Google Test (tests only).
  - `-DQUICK_LINT_JS_USE_BUNDLED_SIMDJSON=OFF`: Use your own copy of simdjson.

## 2.2.0 (2022-02-17)

Downloads

### Fixed

- `x && <Element/>` no longer falsely reports E0026 (missing operand for operator). (Thanks to Piotr Dąbrowski for reporting.)
- In top-level code, `await <x/>` is now parsed as the `await` operator followed by a JSX element (rather than `await` less-than-compared to `x`, followed by jibberish).

### Changed

- Homebrew: Emacs Lisp files are now installed in `<brew>/share/emacs/site-lisp/quick-lint-js` (per `brew audit`'s recommendation) instead of in `share/emacs/site-lisp`.

## 2.1.0 (2022-02-09)

Downloads

### Fixed

- Curried arrow functions like `a => b => { a; b; }` no longer falsely reports E0057. (Thanks to Christian Mund for reporting.)

## 2.0.0 (2022-02-08)

Downloads

### Added

- quick-lint-js now supports JSX syntax in both .js and .jsx files.
- New diagnostics for JSX: E0019, E0181, E0182, E0183, E0186, E0187, E0189, E0191, E0192, E0193
- `if (...) {...} else (...) {...}` now reports E0184 ('missing `if` after `else`') (implemented by Himanshu).
- `if (x = "")` now reports E0188 ('`=` changes variables; to compare, use `===` instead').
- `if (a == "X" || "Y")` now reports E0190 ('missing comparison; `===` does not extend to the right side of `||`').
- `async (param1, param2) {}` now reports E0176 ('missing arrow operator for arrow function'). (E0176 was previously reported only for non-`async` arrow functions.)
- `let x = 'nah'; if (y) { let x = 'yah'; }` now reports E0196 ('new variable shadows existing variable'). This warning is reported only when an assignment (instead of a new variable declaration) was intended.
- `console.log(“hello world”);` now reports E0197 (''“' is not allowed for strings; use " instead').
- `-1 ** 2` now reports E0194 (missing parentheses around left-hand side of `**`).
- `typeof 10 ** 7` now reports E0195 (missing parentheses around operand of `typeof`).

### Fixed

- LSP: When responding to unsupported methods with error code -32601, quick-lint-js now includes the request ID. (Previously, the `"id"` field was always `null`.)
- CLI: If a crash occurs due to E0054 or E0203, the CLI no longer crashes (e.g. with an illegal instruction error).
- quick-lint-js no longer ignores elements of assigned arrays. For example, `[fisrt, second] = s.split(' ');` will now report E0057 for `fisrt` (if `fisrt` is not declared).
- quick-lint-js no longer incorrectly reports E0176 (missing arrow operator for arrow function) if the `extends` clause for a class is parenthesized and contains commas (e.g. `class A extends (B, C) {}`).
- quick-lint-js no longer incorrectly reports E0016, E0038, E0060, or E0207 in tagged template literals. (These errors are still reported for untagged template literals and for string literals.)

### Changed

- Assigning to an imported variable now reports E0185 ('assignment to imported variable') instead of E0003 ('assignment to const variable') (implemented by Matheus de Sousa).

## 1.0.0 (2021-12-13)

Downloads

### Added

- Windows: Clang-cl is now able to compile quick-lint-js for Windows.
- E0176 is now reported if the desired arrow function has more than zero parameters.
- E0178 is now reported if the arrow function appears in top-level code or inside a non-async function.

### Fixed

- Arch Linux: The quick-lint-js package now installs correctly if you have another Vim plugin package installed. The installation error was: "error: failed to commit transaction (conflicting files)"
- `(typeof x)=>{}` and similar code now reports E0151 (invalid function parameter) instead of E0019 (invalid binding in let statement).
- `([(x,)] => {})` now declares `x` as a parameter instead of ignoring `x` entirely. (It still produces E0180).
- `\u0` at the end of a file now reports E0016 (expected hexadecimal digits in Unicode escape sequence) instead of E0038 (unclosed identifier escape sequence)
- `"\u{00a0:"` now reports only one error (E0038 (unclosed identifier escape sequence)) instead of two (E0038 and E0040 (unclosed string literal)).
- After reporting E0178, the arrow function is parsed as if it was async, allowing the body to use `await` as an operator without error.

### Changed

- E0013 is no longer reported for identifiers such as `bird\u{360000}`. E0207 is reported instead.

### Optimized

- The Windows .exe is 51% smaller (2.30 MiB -> 1.14 MiB) by making a hash table used for translations compile-time-only. See the patch here.

## 0.7.1 (2021-12-06)

Beta release.

Downloads

### Added

- npm: The npm package now installs on Windows when using the x86 (32-bit) version of Node.js.
- E0036 is now reported in more situations.

### Fixed

- npm: The npm package now installs on macOS Apple silicon when using the AArch64 (native) version of Node.js. (The package previously worked only on macOS Intel, or when using x86_64 Node.js with Rosetta.)

## 0.7.0 (2021-12-05)

Beta release.

Downloads

### Security

- The source archive (`quick-lint-js-*.tar.gz`) is now signed with our GPG key.
- Arch Linux: The release package on AUR now verifies that the source archive is signed with our GPG key.

### Added

- New diagnostics: E0053, E0179
- Improve error reporting of `console.("hello")` and similar code.
- Reported errors now include a link to the website for a detailed explanation (implemented by Amir).
- CLI: New `--diagnostic-hyperlinks` option (implemented by Amir).
- CLI: Fish and Zsh completions for the `--output-format` option now include documentation for each value (implemented by Amir).

### Fixed

- Reporting E0144 no longer also reports E0057.
- Variables can be named according to Unicode 14 (previously Unicode 13).
- `void 0?a:b=c` no longer reports E0020.
- Vim: The Debian package, the Arch Linux package, and the Homebrew package now install the coc.nvim plugin and the plugin documentation.
- Neovim: Fixed with newer versions of nvim-lspconfig (since commit 97da7ed12e published November 25, 2021).

### Optimized

- Identifier parsing is now SIMD-optimized for ARM systems, including Apple silicon. See the patch here.
- Diagnostic message translations consume less space in executables and also take less time to process. See the patch here.
- Expression ASTs are now garbage-collected during parsing, reducing peak memory usage (and as a side effect making parsing faster). See the patch here.

## 0.6.0 (2021-11-20)

Beta release.

Downloads

### Added

- Various new diagnostics (implemented by Himanshu and Matheus de Sousa).
- VS Code: The new `quick-lint-js.logging` setting allows you to show quick-lint-js' internal log messages in an Output window.
- VS Code: Apple silicon (e.g. M1) (ARM64) is now supported.
- VS Code: Linux ARM (32-bit) is now supported.
- Vim: Improved performance for ALE versions v2.5.0 and newer (and v3.0.0 and newer). You should configure `g:ale_lint_on_text_changed` to `'always'` for the best experience.
- Vim: Improved performance of the ALE plugin by using the LSP server by default.
- The macOS and Windows binaries are now code-signed.
- Emacs (Eglot): You no longer need to type `M-x eglot` in order to start linting. Apply this fix by adding `(eglot-ensure)` to your init file.
- quick-lint-js now understands the `AggregateError`, `FinalizationRegistry`, and `WeakRef` ECMAScript global variables by default.
- The macOS and Windows executables now include embedded code signatures. These signatures are made with a self-signed certificate.
- The Linux executables are now signed with a GPG signature (`.asc` files).
- Vim: coc.nvim is now supported.
- quick-lint-js has a new mascot, Dusty. Say hello! (Artwork by Jenny "Jennipuff" Wheat).
- Translations: German (implemented by Nico Sonack)

### Fixed

- macOS: quick-lint-js no longer hangs if a file is changed in your home directory or project directory.
- Various crashes on invalid code have been fixed.
- quick-lint-js consumes less memory for pathological code patterns.
- VS Code: The extension no longer tries to load an ARM64 DLL on Windows x64.
- The npm package and the manual builds are now much smaller and faster. (They were previously compiled in debug, unoptimized mode.)
- `delete x` no longer reports a warning if `x` is a global variable.
- JSX: Instead of reporting a bunch of errors, quick-lint-js now tells you that JSX syntax is not yet supported.
- FreeBSD: Fixed build.
- E0073, E0094, E0104, E0106, E0111, and E0119 now point to a more helpful place (implemented by strager and Amir).
- `for (let x = a in b; c; d) {}` now reports E0108 instead of reporting E0173, E0110, and E0110 again.

### Changed

- Error codes now have four decimal digits instead of three. For example, E001 is now called E0001.
- LSP benchmarks have been rewritten. The new benchmarks should produce more stable numbers and be fairer to linters with a high start-up time such as Flow.

### Removed

- quick-lint-js no longer looks for files named `.quick-lint-js.config`. To configure quick-lint-js, name your file `quick-lint-js.config` instead.

## 0.5.0 (2021-10-12)

Beta release.

Downloads

### Added

- Various new errors (implemented by Himanshu).
- `quick-lint-js.config` now supports the literally-anything global group. Use this option to disable all use-of-undeclared-variable warnings.
- If quick-lint-js crashes, it will link to a page to report crashes.
- VS Code: The plugin now works on Windows on ARM (64-bit).
- VS Code: The plugin now works on Linux on ARM (32-bit and 64-bit).
- The CLI and LSP server now compile on FreeBSD (amd64). However, we don't provide FreeBSD pre-built executables.
- Neovim: nvim-lspconfig is now supported by quick-lint-js' plugin (implemented by tiagovla).
- VS Code: Contributors can now enable performance tracing (implemented by Jimmy Qiu).

### Fixed

- LSP, VS Code: Filesystem change watching failures no longer crash. These failures can happen on Windows for directories on network shares, for example.
- LSP: Unknown messages no longer crash the LSP server. This makes the LSP server compatible with more clients, such as Neovim's built-in client.
- `break await` and `break yield` no longer incorrectly reports errors (fixed by Himanshu).
- `for (var x = ++y in []) {}` now parses correctly as valid JavaScript.
- Vim: The plugin no longer crashes if a filename contains a newline character (or certain other control characters).
- LSP, VS Code: Config file changes are now recognized properly if any path component contains a symbolic link (Linux and macOS).
- quick-lint-js no longer warns about variables named `__dirname`, `__filename`, `exports`, `module`, or `require` by default.
- Parsing certain code patterns containing `await/` no longer takes excessive memory and time.
- Various crashes on invalid code have been fixed.
- LSP, VS Code: Some memory leaks have been fixed.
- Arch Linux: building should no longer fail with "The install of the quick-lint-js target requires changing an RPATH from the build tree".

## 0.4.0 (2021-09-09)

Beta release.

Downloads

### Changed

- CLI: The `--stdin` option (and `-`) no longer search for configuration files in the current working directory. Use the `--path-for-config-search` option to approximate the old behavior.
- Emacs: For scratch buffers, the Flycheck and Flymake plugins no longer search for configuration files.
- Vim: For unnamed buffers, the ALE plugin no longer searches for configuration files in the current working directory's parent and ancestors. Name the buffer using the `:file` command if you want a configuration file to take effect.
- VS Code: The plugin has been rewritten. Performance should be better, but stability and compatibility might suffer. For example, VS Code on Apple silicon (AArch64 CPUs) has not been tested and will likely no longer work. Please report compatibility issues.

### Added

- Various new errors (implemented by Himanshu)
- CLI: `--path-for-config-search` allows customizing where configuration files are found for `--stdin`
- Global variables for several popular libraries are now recognized by default, including jQuery, Jasmine, and Jest
- Syntax and schema errors in `quick-lint-js.config` no longer crash quick-lint-js. Instead, these errors are highlighted similar to errors in JavaScript files.
- VS Code: `quick-lint-js.config` is now used when linting opened JavaScript files.

### Fixed

- Building quick-lint-js with AddressSanitizer on Fedora no longer fails in `collect-copyright`
- Building quick-lint-js no longer fails if a directory called `brew` exists anywhere in `$PATH`
- Various crashes given invalid JavaScript no longer happen (implemented by wagner riffel and David Vasileff)
- `for (const x of xs)` no longer incorrectly reports E205 (missing initializer in const declaration) (fixed by Himanshu)
- Windows: `quick-lint-js.config` files are now recognized if the containing directory contains non-ASCII characters
- Fix SSE2 corruption on 32-bit Windows builds with MSVC.

## 0.3.0 (2021-07-02)

Beta release.

Downloads

### Security

- Vim plugin: Version 0.2.0 executed `node_modules/.bin/quick-lint-js` without validating that the program is really quick-lint-js. The plugin now conservatively ignores `quick-lint-js` in `node_modules` by default.

### Added

- New JS syntax: `.?`, class fields, `import.meta`, top-level `await`, `#privateProperties`
- Translations: Swedish (implemented by Kim "Linden")
- Emacs plugin (implemented by wagner riffel)
- Neovim plugin
- Errors and warnings are now documented on the website
- Various new errors and error message improvements (implemented by AidenThing, Daniel La Rocque, Erlliam Mejia, Himanshu, Lee Wannacott, Matheus de Sousa)
- Shell completion for the CLI (Bash, Fish, Zsh) (implemented by Shivam Mehta)
- `--stdin` CLI option allows reading JavaScript from standard input instead of a file (implemented by wagner riffel)
- Partially implemented: Global variables can be configured using a `quick-lint-js.config` file

### Fixed

- Using browser variables such as `document` and `window` no longer reports undesired undeclared variable warnings
- `with` statements and `eval` no longer cause spurious undeclared variable warnings (implemented by Himanshu)
- `++a[0];` no longer reports an assignment-to-const-variable error if `a` was declared with `const` (implemented by Himanshu)
- `'undefined' === typeof foo ? 3 : 4` no longer reports a warning that `foo` is undeclared (implemented by Himanshu)
- Building tests with GCC 11.1.1 no longer fails due to `-Werror`
- Various crashes given invalid JavaScript no longer happen
- Building the VS Code plugin now works on Windows (implemented by Jimmy Qiu)

## 0.2.0 (2021-04-05)

Beta release.

Downloads