#### TypeScript: Support for TypeScript 3.7 ([#6657] by [@cryrivers]) Prettier 1.19 adds support for the features of the upcoming TypeScript 3.7 that introduce new syntax: - [Optional chaining](https://devblogs.microsoft.com/typescript/announcing-typescript-3-7-rc/#optional-chaining) - [Nullish coalescing](https://devblogs.microsoft.com/typescript/announcing-typescript-3-7-rc/#nullish-coalescing) - [Assertion functions](https://devblogs.microsoft.com/typescript/announcing-typescript-3-7-rc/#assertion-functions) - [`declare` modifier on class fields](https://github.com/microsoft/TypeScript/pull/33509) **NOTE:** A dependency upgrade for TypeScript 3.7 led to dropping Node 6 support for direct installation from GitHub. Prettier installed from NPM stays compatible with Node 4. ##### Optional Chaining ```ts // Input const longChain = obj?.a?.b?.c?.d?.e?.f?.g; const longChainCallExpression = obj.a?.(a,b,c).b?.(a,b,c).c?.(a,b,c).d?.(a,b,c).e?.(a,b,c).f?.(a,b,c) // Output (Prettier master) const longChain = obj?.a?.b?.c?.d?.e?.f?.g; const longChainCallExpression = obj .a?.(a, b, c) .b?.(a, b, c) .c?.(a, b, c) .d?.(a, b, c) .e?.(a, b, c) .f?.(a, b, c); ``` ##### Nullish Coalescing ```ts // Input const cond = null; const result = cond??'a'; const longChain = cond??cond??cond??'b'; // Output (Prettier master) const cond = null; const result = cond ?? "a"; const longChain = cond ?? cond ?? cond ?? "b"; ``` ##### Assertion Functions ```ts // Input function assertsString(x: any): asserts x {console.assert(typeof x === 'string');} function assertsStringWithGuard(x: any): asserts x is string {console.assert(typeof x === 'string');} // Output (Prettier master) function assertsString(x: any): asserts x { console.assert(typeof x === "string"); } function assertsStringWithGuard(x: any): asserts x is string { console.assert(typeof x === "string"); } ``` ##### `declare` Modifier on Class Fields ```ts // Input class B {p: number;} class C extends B {declare p: 256 | 1000;} // Output (Prettier master) class B { p: number; } class C extends B { declare p: 256 | 1000; } ``` #### TypeScript: Fix optional computed class fields and methods ([#6657] by [@cryrivers], [#6673] by [@thorn0]) Still broken if the key is a complex expression, but has been fixed in these cases: ```ts // Input class Foo { [bar]?: number; protected [s]?() {} } // Output (Prettier stable) class Foo { [bar]: number; protected [s?]() {}; } // Output (Prettier master) class Foo { [bar]?: number; protected [s]?() {} } ``` #### API: Add `resolveConfig` option to `getFileInfo()` ([#6666] by [@kaicataldo]) Add a `resolveConfig: boolean` option to `prettier.getFileInfo()` that, when set to `true`, will resolve the configuration for the given file path. This allows consumers to take any overridden parsers into account. #### JavaScript: Add support for [partial application syntax](https://github.com/tc39/proposal-partial-application) ([#6397] by [@JounQin]) ```js // Input const addOne = add(1, ?); // apply from the left addOne(2); // 3 const addTen = add(?, 10); // apply from the right addTen(2); // 12 // with pipeline let newScore = player.score |> add(7, ?) |> clamp(0, 100, ?); // shallow stack, the pipe to `clamp` is the same frame as the pipe to `add`. // Output (Prettier stable) SyntaxError: Unexpected token (1:23) > 1 | const addOne = add(1, ?); // apply from the left | ^ 2 | addOne(2); // 3 3 | 4 | const addTen = add(?, 10); // apply from the right // Output (Prettier master) const addOne = add(1, ?); // apply from the left addOne(2); // 3 const addTen = add(?, 10); // apply from the right addTen(2); // 12 // with pipeline let newScore = player.score |> add(7, ?) |> clamp(0, 100, ?); // shallow stack, the pipe to \`clamp\` is the same frame as the pipe to \`add\`. ``` #### JavaScript: More readable parentheses for `new` call ([#6412] by [@bakkot]) ```js // Input var a = new (x().y)(); var a = new (x().y.z)(); var a = new (x().y().z)(); // Output (Prettier stable) var a = new (x()).y(); var a = new (x()).y.z(); var a = new (x().y()).z(); // Output (Prettier master) var a = new (x().y)(); var a = new (x().y.z)(); var a = new (x().y().z)(); ``` #### MDX: Text following JSX was trimmed incorrectly ([#6340] by [@JounQin]) ```md # Heading test test 123 test test 123 test test 123 ``` #### TypeScript/Flow: Fix indentation for union types inside tuples ([#6381] by [@squidfunk], [#6605] by [@thorn0]) ```ts // Input type A = [ | AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD ] type B = [ | AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD, | AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD ] type C = [ | [AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD] | [AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD] ] // Output (Prettier stable) type A = [ | AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD ]; type B = [ | AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD, | AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD ]; type C = [ | [ | AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD ] | [ | AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD ] ]; // Output (Prettier master) type A = [ | AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD ]; type B = [ ( | AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD ), ( | AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD ) ]; type C = [ | [ | AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD ] | [ | AAAAAAAAAAAAAAAAAAAAAA | BBBBBBBBBBBBBBBBBBBBBB | CCCCCCCCCCCCCCCCCCCCCC | DDDDDDDDDDDDDDDDDDDDDD ] ]; ``` #### MDX: Adjacent JSX elements should be allowed ([#6332] by [@JounQin]) ```jsx // Input test test 123 // Output (Prettier stable) SyntaxError: Unexpected token (3:9) 1 | 2 | test test > 3 | 123 | ^ // Output (Prettier master) test test 123 // Input test test test test 123 // Output (Prettier stable) SyntaxError: Adjacent JSX elements must be wrapped in an enclosing tag. Did you want a JSX fragment <>...? (4:1) 2 | test test 3 | > 4 | | ^ 5 | test test 6 | 123 // Output (Prettier master) test test test test 123 ``` #### TypeScript: Comments after JSX element names with type arguments were lost ([#6209] by [@duailibe]) ```ts // Input const comp = ( // This comment goes missing value={4} > Test ); // Output (Prettier stable) const comp = value={4}>Test; // Output (Prettier master) const comp = ( // This comment goes missing value={4} > Test ); ``` #### Handlebars: Avoid adding unwanted line breaks between text and mustaches ([#6186] by [@gavinjoyce]) Previously, Prettier added line breaks between text and mustaches which resulted in unwanted whitespace in rendered output. ```hbs

Your username is @{{name}}

Hi {{firstName}} {{lastName}}

Your username is @ {{name}}

Hi {{firstName}} {{lastName}}

Your username is @{{name}}

Hi {{firstName}} {{lastName}}

``` #### Handlebars: Improve comment formatting ([#6206] by [@gavinjoyce]) Previously, Prettier would sometimes ignore whitespace when formatting comments. ```hbs
{{! Foo }} {{#if @foo}} Foo {{/if}} {{! Bar }} {{#if @bar}} Bar {{/if}}
{{! Foo }} {{#if @foo}} Foo {{/if}}{{! Bar }}{{#if @bar}} Bar {{/if}}
{{! Foo }} {{#if @foo}} Foo {{/if}} {{! Bar }} {{#if @bar}} Bar {{/if}}
``` #### JavaScript: Update `??` precedence to match stage 3 proposal ([#6404] by [@vjeux]) We've updated Prettier's support for the nullish coalescing operator to match a spec update that no longer allows it to immediately contain, or be contained within an `&&` or `||` operation. ```js // Input (foo ?? baz) || baz; // Output (Prettier stable) foo ?? baz || baz; // Output (Prettier master) (foo ?? baz) || baz; ``` Please note, as we update our parsers with versions that support this spec update, code without the parenthesis will throw a parse error. #### JavaScript: Keep parentheses with comments in unary expressions ([#6217] by [@sosukesuzuki]) ```ts // Input !( /* foo */ foo ); !( foo // foo ); // Output (Prettier stable) !/* foo */ foo; !foo; // foo // Output (Prettier master) !(/* foo */ foo); !( foo // foo ); ``` #### Javascript: Use function literals in arguments to detect function composition ([#6033] by [@brainkim]) Previously, we used a set of hard-coded names related to functional programming (`compose`, `flow`, `pipe`, etc.) to detect function composition and chaining patterns in code. This was done so that Prettier would not put code like the following call to `pipe` on the same line even if it fit within the allotted column budget: ```js source$ .pipe( filter(x => x % 2 === 0), map(x => x + x), scan((acc, x) => acc + x, 0), ) .subscribe(x => console.log(x)); ``` However, this heuristic caused people to complain because of false positives where calls to functions or methods matching the hard-coded names would always be split on multiple lines, even if the calls did not contain function arguments ([#5769](https://github.com/prettier/prettier/issues/5769), [#5969](https://github.com/prettier/prettier/issues/5969)). For many, this blanket decision to split functions based on name was both surprising and sub-optimal. We now use a refined heuristic which uses the presence of function literals to detect function composition. This heuristic preserves the line-splitting behavior above and eliminates many if not all of the false positives caused by the older heuristic. We encourage prettier users to try out the new heuristic and provide feedback. ```js // Input eventStore.update(id, _.flow(updater, incrementVersion)); // Output (Prettier stable) eventStore.update( id, _.flow( updater, incrementVersion ) ); // Output (Prettier master) eventStore.update(id, _.flow(updater, incrementVersion)); ``` #### Handlebars: Preserve HTML entities ([#6234] by [@gavinjoyce]) ```hbs

Some escaped characters: < > &

Some escaped characters: < > &

Some escaped characters: < > &

``` #### JavaScript: Stop moving comments inside tagged template literals ([#6236] by [@sosukesuzuki]) ```js // Input foo //comment ` `; // Output (Prettier stable) foo` // comment `; // Output (Prettier master) foo // comment ` `; ``` #### TypeScript/Flow: Fix moving comments in function calls like `useEffect` ([#6270] by [@sosukesuzuki]) This fixes a bug that was affecting function calls with an arrow function as the first argument and an array expression as the second argument, e.g. React's `useEffect`. If a comment was placed on the line before the second argument, Prettier would move it to the line above and corrupt the indentation. The bug was only present when using the Flow and TypeScript parsers. ```js // Input useEffect( () => { console.log("some code", props.foo); }, // eslint-disable-line react-hooks/exhaustive-deps [] ); // Output (Prettier stable) useEffect(() => { console.log("some code", props.foo); }, // eslint-disable-line react-hooks/exhaustive-deps []); // Output (Prettier master) useEffect( () => { console.log("some code", props.foo); }, // eslint-disable-line react-hooks/exhaustive-deps [] ); ``` #### TypeScript: Fix crashes when using `//` in JSX texts ([#6289] by [@duailibe]) This version updates the TypeScript parser to correctly handle JSX text with double slashes (`//`). In previous versions, this would cause Prettier to crash. #### HTML, Vue: Don't wrap `template` elements on lines shorter than `printWidth` ([#6284] by [@sosukesuzuki]) Previously, even if the line length was shorter than `printWidth`, Prettier would break the line with a `template` element. ```html ``` #### HTML: Add support for `!` and other entities ([#6785] by [@lydell]) Previously, Prettier only supported the most common HTML entities, such as ` ` and `"`. Now, Prettier supports every HTML entity in the HTML spec, such as `!` and `⋔`. ```html

Hi!

Hi!

``` #### JavaScript: Empty lines in destructured arrow function parameters could break indentation and idempotence ([#6301] & [#6382] by [@sosukesuzuki]) Previously, Prettier indented code strangely when an arrow function whose parameters included an object pattern was passed to a function call as an argument. Also, it broke idempotence. Please see [#6294](https://github.com/prettier/prettier/issues/6294) for details. ```js // Input foo( ({ a, b }) => {} ); // Output (Prettier stable) foo(({ a, b }) => {}); // Output (Prettier master) foo( ({ a, b }) => {} ); ``` #### TypeScript: Put a closing parenthesis onto a new line after union types ([#6307] by [@sosukesuzuki]) ```ts // Input const foo = [abc, def, ghi, jkl, mno, pqr, stu, vwx, yz] as ( | string | undefined )[]; // Prettier (stable) const foo = [abc, def, ghi, jkl, mno, pqr, stu, vwx, yz] as ( | string | undefined)[]; // Prettier (master) const foo = [abc, def, ghi, jkl, mno, pqr, stu, vwx, yz] as ( | string | undefined )[]; ``` #### HTML: Script tags are now treated as blocks for the purposes of formatting ([#6423] by [@thorn0]) Previously, in the [whitespace-sensitive mode](https://prettier.io/docs/en/options.html#html-whitespace-sensitivity), they were formatted as if they were inline. ```html ``` #### TypeScript: Correctly format long one-line mapped types in one pass ([#6420] by [@sosukesuzuki]) Previously, when Prettier formatted long one-line mapped types, it would break the line but didn’t add a semicolon until you ran Prettier again, which means Prettier’s idempotence rule was broken. Now, Prettier adds the semicolon in the first run. ```ts // Input type FooBar = { [P in keyof T]: T[P] extends Something ? Something : T[P] } // Prettier (stable) type FooBar = { [P in keyof T]: T[P] extends Something ? Something : T[P] }; // Prettier (master) type FooBar = { [P in keyof T]: T[P] extends Something ? Something : T[P]; }; ``` #### JavaScript: Fix formatting of object destructuring with parameter decorators ([#6411] by [@sosukesuzuki]) Previously, Prettier formatted decorators for destructured parameters in a weird way. Now, parameter decorators are placed just above the parameter they belong to. ```js // Input class Class { method( @decorator { foo } ) {} } // Prettier (stable) class Class { method(@decorator { foo }) {} } // Prettier (master) class Class { method( @decorator { foo } ) {} } ``` #### JavaScript: Handle empty object patterns with type annotations in function parameters ([#6438] by [@bakkot]) ```js // Input const f = ({}: MyVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongType) => {}; function g({}: Foo) {} // Output (Prettier stable) const f = ({ , }: MyVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongType) => {}; function g({ }: Foo) {} // Output (Prettier master) const f = ({}: MyVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongType) => {}; function g({}: Foo) {} ``` #### JavaScript: Put a closing parenthesis onto a new line after binary expressions within function calls ([#6441] by [@sosukesuzuki]) ```js // Input ( aaaaaaaaaaaaaaaaaaaaaaaaa && bbbbbbbbbbbbbbbbbbbbbbbbb && ccccccccccccccccccccccccc && ddddddddddddddddddddddddd && eeeeeeeeeeeeeeeeeeeeeeeee )(); // Prettier (stable) (aaaaaaaaaaaaaaaaaaaaaaaaa && bbbbbbbbbbbbbbbbbbbbbbbbb && ccccccccccccccccccccccccc && ddddddddddddddddddddddddd && eeeeeeeeeeeeeeeeeeeeeeeee)(); // Prettier (master) ( aaaaaaaaaaaaaaaaaaaaaaaaa && bbbbbbbbbbbbbbbbbbbbbbbbb && ccccccccccccccccccccccccc && ddddddddddddddddddddddddd && eeeeeeeeeeeeeeeeeeeeeeeee )(); ``` #### JavaScript: Fix formatting of long named exports ([#6446] by [@sosukesuzuki]) Now, Prettier formats them the same way it formats named imports. ```js // Input export { fooooooooooooooooooooooooooooooooooooooooooooooooo } from "fooooooooooooooooooooooooooooo"; // Prettier (stable) export { fooooooooooooooooooooooooooooooooooooooooooooooooo } from "fooooooooooooooooooooooooooooo"; // Prettier (master) export { fooooooooooooooooooooooooooooooooooooooooooooooooo } from "fooooooooooooooooooooooooooooo"; ``` #### JavaScript: Fix bad formatting for multi-line optional chaining with comment ([#6506] by [@sosukesuzuki]) ```js // Input return a .b() .c() // Comment ?.d() // Prettier (stable) return a .b() .c() ?.// Comment d(); // Prettier (master) return ( a .b() .c() // Comment ?.d() ); ``` #### JavaScript: Fix inconsistent indentation in switch statement ([#6514] by [@sosukesuzuki]) ```js // Input switch ($veryLongAndVeryVerboseVariableName && $anotherVeryLongAndVeryVerboseVariableName) { } switch ($longButSlightlyShorterVariableName && $anotherSlightlyShorterVariableName) { } // Prettier (stable) switch ( $veryLongAndVeryVerboseVariableName && $anotherVeryLongAndVeryVerboseVariableName ) { } switch ( $longButSlightlyShorterVariableName && $anotherSlightlyShorterVariableName ) { } // Prettier (master) switch ( $veryLongAndVeryVerboseVariableName && $anotherVeryLongAndVeryVerboseVariableName ) { } switch ( $longButSlightlyShorterVariableName && $anotherSlightlyShorterVariableName ) { } ``` #### TypeScript: Keep type parameters inline for type annotations in variable declarations ([#6467] by [@sosukesuzuki]) ```ts // Input const fooooooooooooooo: SomeThing = looooooooooooooooooooooooooooooongNameFunc(); // Prettier (stable) const fooooooooooooooo: SomeThing< boolean > = looooooooooooooooooooooooooooooongNameFunc(); // Prettier (master) const fooooooooooooooo: SomeThing = looooooooooooooooooooooooooooooongNameFunc(); ``` #### Handlebars: Fix `--single-quote` option on HTML attributes ([#6377] by [@dcyriller]) Previously, the flag was not applied on HTML attributes. ```hbs
``` #### TypeScript: Sometimes double parentheses around types were removed incorrectly ([#6604] by [@sosukesuzuki]) ```ts // Input type A = 0 extends ((1 extends 2 ? 3 : 4)) ? 5 : 6; type B = ((0 extends 1 ? 2 : 3)) extends 4 ? 5 : 6; type C = ((number | string))["toString"]; type D = ((keyof T1))["foo"]; // Prettier (stable) type A = 0 extends 1 extends 2 ? 3 : 4 ? 5 : 6; type B = 0 extends 1 ? 2 : 3 extends 4 ? 5 : 6; type C = number | string["toString"]; type D = keyof T1["foo"]; // Prettier (master) type A = 0 extends (1 extends 2 ? 3 : 4) ? 5 : 6; type B = (0 extends 1 ? 2 : 3) extends 4 ? 5 : 6; type C = (number | string)["toString"]; type D = (keyof T1)["foo"]; ``` #### JavaScript: Support formatting code with V8 intrinsics ([#6496] by [@rreverser]) ```js // Input function doSmth() { %DebugPrint ( foo ) } // Prettier (stable) SyntaxError: Unexpected token (2:13) 1 | function doSmth() { > 2 | %DebugPrint | ^ // Prettier (master) function doSmth() { %DebugPrint(foo); } ``` #### TypeScript: Sometimes removing parentheses around JSX made the code unparseable ([#6640] by [@sosukesuzuki]) ```tsx // Input ().toString(); // Prettier (stable) .toString(): // Prettier (master) ().toString(); ``` #### JavaScript: Object destructuring in method parameters always broke into multiple lines ([#6646] by [@ericsakmar]) ```js // Input const obj = { func(id, { blog: { title } }) { return id + title; }, }; class A { func(id, { blog: { title } }) { return id + title; } #func(id, { blog: { title } }) { return id + title; } } // Prettier (stable) const obj = { func( id, { blog: { title } } ) { return id + title; } }; class A { func( id, { blog: { title } } ) { return id + title; } #func( id, { blog: { title } } ) { return id + title; } } // Prettier (master) const obj = { func(id, { blog: { title } }) { return id + title; }, }; class A { func(id, { blog: { title } }) { return id + title; } #func(id, { blog: { title } }) { return id + title; } } ``` #### Angular: Put a closing parenthesis onto a new line after ternaries passed to pipes ([#5682] by [@selvazhagan]) ```html {{ (isCustomDiscount ? 'DISCOUNTS__DISCOUNT_TRAINING_HEADER__CUSTOM_DISCOUNT' : 'DISCOUNTS__DISCOUNT_TRAINING_HEADER__DISCOUNT') | translate }} {{ (isCustomDiscount ? "DISCOUNTS__DISCOUNT_TRAINING_HEADER__CUSTOM_DISCOUNT" : "DISCOUNTS__DISCOUNT_TRAINING_HEADER__DISCOUNT") | translate }} {{ (isCustomDiscount ? "DISCOUNTS__DISCOUNT_TRAINING_HEADER__CUSTOM_DISCOUNT" : "DISCOUNTS__DISCOUNT_TRAINING_HEADER__DISCOUNT" ) | translate }} ``` #### Handlebars: Fix handling of whitespace and line breaks ([#6354] by [@chadian]) This fixes a variety of whitespace and line break use cases within Handlebars and Glimmer templates. ```hbs {{name}} Some sentence with {{dynamic}} expressions. sometimes{{nogaps}}areimportant {{name}} is your name {{name}} Some sentence with {{dynamic}} expressions. sometimes {{nogaps}} areimportant {{name}} is your name {{name}} Some sentence with {{dynamic}} expressions. sometimes{{nogaps}}areimportant {{name}} is your name ``` #### Angular: Add formatting for `i18n` attributes ([#6695] by [@voithos]) Prettier will auto-wrap the contents of `i18n` attributes once they exceed the line length. ```html

Hello!

Hello!

Hello!

``` #### JavaScript: Break arrays of arrays/objects if each element has more than one element/property ([#6694] by [@sosukesuzuki]) ```js // Input test.each([ { a: "1", b: 1 }, { a: "2", b: 2 }, { a: "3", b: 3 } ])("test", ({ a, b }) => { expect(Number(a)).toBe(b); }); [[0, 1, 2], [0, 1, 2]]; new Map([ [A, B], [C, D], [E, F], [G, H], [I, J], [K, L], [M, N] ]); // Output (Prettier stable) test.each([{ a: "1", b: 1 }, { a: "2", b: 2 }, { a: "3", b: 3 }])( "test", ({ a, b }) => { expect(Number(a)).toBe(b); } ); [[0, 1, 2], [0, 1, 2]] new Map([[A, B], [C, D], [E, F], [G, H], [I, J], [K, L], [M, N]]); // Output (Prettier master) test.each([ { a: "1", b: 1 }, { a: "2", b: 2 }, { a: "3", b: 3 } ])("test", ({ a, b }) => { expect(Number(a)).toBe(b); }); [ [0, 1, 2], [0, 1, 2] ]; new Map([ [A, B], [C, D], [E, F], [G, H], [I, J], [K, L], [M, N] ]); ``` #### TypeScript: Keep semi for a class property before index signature when no-semi is enabled ([#6728] by [@sosukesuzuki]) Attempting to format Prettier’s output again used to result in a syntax error. ```ts // Input export class User { id: number = 2; [key: string]: any } // Output (Prettier stable) export class User { id: number = 2 [key: string]: any } // Output (Prettier master) export class User { id: number = 2; [key: string]: any } ``` #### Flow: Parentheses around arrow functions' return types that have `FunctionTypeAnnotation` nested in `ObjectTypeAnnotation` ([#6717] by [@sosukesuzuki]) This is a workaround for a [bug](https://github.com/facebook/flow/pull/8163) in the Flow parser. Without the parentheses, the parser throws an error. ```js // Input const example1 = (): { p: (string => string) } => (0: any); // Output (Prettier stable) const example1 = (): { p: string => string } => (0: any); // Output (Prettier master) const example1 = (): ({ p: string => string }) => (0: any); ``` #### CLI: Handle errors when reading stdin ([#6708] by [@andersk] and [@lydell]) If you had an error in your `.prettierrc` Prettier used to crash when formatting stdin. Such errors are now handled properly. ``` # Prettier stable $ prettier --parser babel < test.js (node:21531) UnhandledPromiseRejectionWarning: Error: Invalid printWidth value. Expected an integer, but received "nope". at _loop (/home/lydell/forks/prettier/node_modules/prettier/bin-prettier.js:7887:63) at Normalizer._applyNormalization (/home/lydell/forks/prettier/node_modules/prettier/bin-prettier.js:8000:13) at applyNormalization (/home/lydell/forks/prettier/node_modules/prettier/bin-prettier.js:7817:49) at Normalizer.normalize (/home/lydell/forks/prettier/node_modules/prettier/bin-prettier.js:7823:9) at normalizeOptions$1 (/home/lydell/forks/prettier/node_modules/prettier/bin-prettier.js:8760:31) at Object.normalizeApiOptions (/home/lydell/forks/prettier/node_modules/prettier/bin-prettier.js:8918:10) at getOptionsForFile (/home/lydell/forks/prettier/node_modules/prettier/bin-prettier.js:44160:69) at /home/lydell/forks/prettier/node_modules/prettier/bin-prettier.js:44214:22 at process._tickCallback (internal/process/next_tick.js:68:7) (node:21531) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1) (node:21531) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code. # Prettier master $ prettier --parser babel < test.js [error] Invalid printWidth value. Expected an integer, but received "nope". ``` #### CLI: Gracefully handle nonexistent paths passed to --stdin-filepath ([#6687] by [@voithos]) Previously, if you passed a nonexistent subdirectory to --stdin-filepath, Prettier would throw an error. Now, Prettier gracefully handles this. ``` # Prettier stable $ prettier --stdin-filepath does/not/exist.js < test.js [error] Invalid configuration file: ENOENT: no such file or directory, scandir '/home/lydell/forks/prettier/does/not' # Prettier master $ prettier --stdin-filepath does/not/exist.js < test.js test; ``` #### JavaScript: Numeric separators were removed from BigInt literals ([#6796] by [@thorn0]) ```js // Input const bigints = [200_000n, 0x0000_000An, 0b0111_1111n]; // Output (Prettier stable) const bigints = [200000n, 0x0000000an, 0b01111111n]; // Output (Prettier master) const bigints = [200_000n, 0x0000_000an, 0b0111_1111n]; ``` [#5682]: https://github.com/prettier/prettier/pull/5682 [#6657]: https://github.com/prettier/prettier/pull/6657 [#5910]: https://github.com/prettier/prettier/pull/5910 [#6033]: https://github.com/prettier/prettier/pull/6033 [#6186]: https://github.com/prettier/prettier/pull/6186 [#6206]: https://github.com/prettier/prettier/pull/6206 [#6209]: https://github.com/prettier/prettier/pull/6209 [#6217]: https://github.com/prettier/prettier/pull/6217 [#6234]: https://github.com/prettier/prettier/pull/6234 [#6236]: https://github.com/prettier/prettier/pull/6236 [#6270]: https://github.com/prettier/prettier/pull/6270 [#6284]: https://github.com/prettier/prettier/pull/6284 [#6785]: https://github.com/prettier/prettier/pull/6785 [#6289]: https://github.com/prettier/prettier/pull/6289 [#6301]: https://github.com/prettier/prettier/pull/6301 [#6307]: https://github.com/prettier/prettier/pull/6307 [#6332]: https://github.com/prettier/prettier/pull/6332 [#6340]: https://github.com/prettier/prettier/pull/6340 [#6354]: https://github.com/prettier/prettier/pull/6354 [#6377]: https://github.com/prettier/prettier/pull/6377 [#6381]: https://github.com/prettier/prettier/pull/6381 [#6382]: https://github.com/prettier/prettier/pull/6382 [#6397]: https://github.com/prettier/prettier/pull/6397 [#6404]: https://github.com/prettier/prettier/pull/6404 [#6411]: https://github.com/prettier/prettier/pull/6411 [#6412]: https://github.com/prettier/prettier/pull/6412 [#6420]: https://github.com/prettier/prettier/pull/6420 [#6423]: https://github.com/prettier/prettier/pull/6423 [#6438]: https://github.com/prettier/prettier/pull/6411 [#6441]: https://github.com/prettier/prettier/pull/6441 [#6446]: https://github.com/prettier/prettier/pull/6446 [#6467]: https://github.com/prettier/prettier/pull/6467 [#6496]: https://github.com/prettier/prettier/pull/6496 [#6506]: https://github.com/prettier/prettier/pull/6506 [#6514]: https://github.com/prettier/prettier/pull/6514 [#6604]: https://github.com/prettier/prettier/pull/6604 [#6605]: https://github.com/prettier/prettier/pull/6605 [#6640]: https://github.com/prettier/prettier/pull/6640 [#6646]: https://github.com/prettier/prettier/pull/6646 [#6666]: https://github.com/prettier/prettier/pull/6666 [#6673]: https://github.com/prettier/prettier/pull/6673 [#6695]: https://github.com/prettier/prettier/pull/6695 [#6694]: https://github.com/prettier/prettier/pull/6694 [#6717]: https://github.com/prettier/prettier/pull/6717 [#6728]: https://github.com/prettier/prettier/pull/6728 [#6708]: https://github.com/prettier/prettier/pull/6708 [#6687]: https://github.com/prettier/prettier/pull/6687 [#6796]: https://github.com/prettier/prettier/pull/6796 [@brainkim]: https://github.com/brainkim [@duailibe]: https://github.com/duailibe [@gavinjoyce]: https://github.com/gavinjoyce [@sosukesuzuki]: https://github.com/sosukesuzuki [@g-harel]: https://github.com/g-harel [@jounqin]: https://github.com/JounQin [@bakkot]: https://gibhub.com/bakkot [@thorn0]: https://github.com/thorn0 [@dcyriller]: https://github.com/dcyriller [@rreverser]: https://github.com/RReverser [@ericsakmar]: https://github.com/ericsakmar [@squidfunk]: https://github.com/squidfunk [@vjeux]: https://github.com/vjeux [@selvazhagan]: https://github.com/selvazhagan [@chadian]: https://github.com/chadian [@kaicataldo]: https://github.com/kaicataldo [@cryrivers]: https://github.com/Cryrivers [@voithos]: https://github.com/voithos [@andersk]: https://github.com/andersk [@lydell]: https://github.com/lydell