Change default of singleQuote to true

changelog_unreleased/api/pr-7466.md

@@ -0,0 +1,18 @@
+#### Change default value for `singleQuotes` to `true` ([#7466](https://github.com/prettier/prettier/pull/7466) by [@karlhorky](https://github.com/karlhorky))
+
+[Since version 0.0.1](https://github.com/prettier/prettier/commit/599b4311bb6be9204689a7725d37d6fdfca770aa), Prettier has an [option](https://prettier.io/docs/en/options.html#quotes) to use single quotes instead of double quotes.
+Since version 2.0, the default of this option changes from `false` to `true`.
+
+<!-- prettier-ignore -->
+```js
+// Input
+const foo = 'bar';
+// Prettier stable
+const foo = "bar";
+// Prettier master
+const foo = 'bar';
+```
+
+The JavaScript ecosystem has largely standardized on single quotes, with it being the most popular style seen in the wild.
+
+If the old behavior is still preferred, please configure Prettier with `{ "singleQuotes": false }`.

docs/options.md

@@ -56,6 +56,8 @@ Valid options:
 
 ## Quotes
 
+_The default value changed from `false` to `true` in v2.0.0_
+
 Use single quotes instead of double quotes.
 
 Notes:
@@ -67,7 +69,7 @@ See the [strings rationale](rationale.md#strings) for more information.
 
 | Default | CLI Override     | API Override          |
 | ------- | ---------------- | --------------------- |
-| `false` | `--single-quote` | `singleQuote: <bool>` |
+| `true`  | `--single-quote` | `singleQuote: <bool>` |
 
 ## Quote Props
 

docs/rationale.md

@@ -13,7 +13,7 @@ The first requirement of Prettier is to output valid code that has the exact sam
 
 ### Strings
 
-Double or single quotes? Prettier chooses the one which results in the fewest number of escapes. `"It's gettin' better!"`, not `'It\'s gettin\' better!'`. In case of a tie, Prettier defaults to double quotes (but that can be changed via the [`--single-quote`](options.html#quotes) option).
+Double or single quotes? Prettier follows the JavaScript ecosystem, which has largely standardized on single quotes, with it being the most popular style seen in the wild.
 
 JSX has its own option for quotes: [`--jsx-single-quote`](options.html#jsx-quotes).
 JSX takes its roots from HTML, where the dominant use of quotes for attributes is double quotes. Browser developer tools also follow this convention by always displaying HTML with double quotes, even if the source code uses single quotes. A separate option allows using single quotes for JS and double quotes for "HTML" (JSX).

src/common/common-options.js

@@ -16,7 +16,10 @@ module.exports = {
     since: "0.0.0",
     category: CATEGORY_COMMON,
     type: "boolean",
-    default: false,
+    default: [
+      { since: "0.0.0", value: false },
+      { since: "2.0.0", value: true }
+    ],
     description: "Use single quotes instead of double quotes."
   },
   proseWrap: {

tests/angular_component_examples/__snapshots__/jsfmt.spec.js.snap

@@ -27,7 +27,7 @@ class     TestComponent {}
 
 =====================================output=====================================
 @Component({
-  selector: "app-test",
+  selector: 'app-test',
   template: \`
     <ul>
       <li>test</li>
@@ -75,7 +75,7 @@ class     TestComponent {}
 
 =====================================output=====================================
 @Component({
-  selector: "app-test",
+  selector: 'app-test',
   template: \`
     <ul>
       <li>test</li>

tests/angular_interpolation/__snapshots__/jsfmt.spec.js.snap

@@ -109,7 +109,7 @@ trailingComma: "none"
   a[b | c],
   ($students | async).items,
   ($students | async)(),
-  myData | myPipe: "arg1":"arg2":"arg3",
+  myData | myPipe: 'arg1':'arg2':'arg3',
   value
     | pipeA
       : {
@@ -122,8 +122,8 @@ trailingComma: "none"
         }
     | aaa,
   (hideLinqPanel
-    ? "ReportSelection.HideShowLabel_Show.String"
-    : "ReportSelection.HideShowLabel_Hide.String"
+    ? 'ReportSelection.HideShowLabel_Show.String'
+    : 'ReportSelection.HideShowLabel_Hide.String'
   ) | localize: localizationSection
 ]
 ================================================================================
@@ -175,7 +175,7 @@ printWidth: 80
   a[b | c],
   ($students | async).items,
   ($students | async)(),
-  myData | myPipe: "arg1":"arg2":"arg3",
+  myData | myPipe: 'arg1':'arg2':'arg3',
   value
     | pipeA
       : {
@@ -188,8 +188,8 @@ printWidth: 80
         }
     | aaa,
   (hideLinqPanel
-    ? "ReportSelection.HideShowLabel_Show.String"
-    : "ReportSelection.HideShowLabel_Hide.String"
+    ? 'ReportSelection.HideShowLabel_Show.String'
+    : 'ReportSelection.HideShowLabel_Hide.String'
   ) | localize: localizationSection
 ]
 ================================================================================
@@ -242,7 +242,7 @@ trailingComma: "all"
   a[b | c],
   ($students | async).items,
   ($students | async)(),
-  myData | myPipe: "arg1":"arg2":"arg3",
+  myData | myPipe: 'arg1':'arg2':'arg3',
   value
     | pipeA
       : {
@@ -255,8 +255,8 @@ trailingComma: "all"
         }
     | aaa,
   (hideLinqPanel
-    ? "ReportSelection.HideShowLabel_Show.String"
-    : "ReportSelection.HideShowLabel_Hide.String"
+    ? 'ReportSelection.HideShowLabel_Show.String'
+    : 'ReportSelection.HideShowLabel_Hide.String'
   ) | localize: localizationSection
 ]
 ================================================================================

tests/arrow-call/__snapshots__/jsfmt.spec.js.snap

@@ -56,33 +56,33 @@ const testResults = results.testResults.map((testResult) =>
   formatResult(testResult, formatter, reporter)
 );
 
-it("mocks regexp instances", () => {
+it('mocks regexp instances', () => {
   expect(() =>
     moduleMocker.generateFromMetadata(moduleMocker.getMetadata(/a/))
   ).not.toThrow();
 });
 
-expect(() => asyncRequest({ url: "/test-endpoint" })).toThrowError(
+expect(() => asyncRequest({ url: '/test-endpoint' })).toThrowError(
   /Required parameter/
 );
 
 expect(() =>
-  asyncRequest({ url: "/test-endpoint-but-with-a-long-url" })
+  asyncRequest({ url: '/test-endpoint-but-with-a-long-url' })
 ).toThrowError(/Required parameter/);
 
 expect(() =>
-  asyncRequest({ url: "/test-endpoint-but-with-a-suuuuuuuuper-long-url" })
+  asyncRequest({ url: '/test-endpoint-but-with-a-suuuuuuuuper-long-url' })
 ).toThrowError(/Required parameter/);
 
 expect(() =>
-  asyncRequest({ type: "foo", url: "/test-endpoint" })
+  asyncRequest({ type: 'foo', url: '/test-endpoint' })
 ).not.toThrowError();
 
 expect(() =>
-  asyncRequest({ type: "foo", url: "/test-endpoint-but-with-a-long-url" })
+  asyncRequest({ type: 'foo', url: '/test-endpoint-but-with-a-long-url' })
 ).not.toThrowError();
 
-const a = Observable.fromPromise(axiosInstance.post("/carts/mine")).map(
+const a = Observable.fromPromise(axiosInstance.post('/carts/mine')).map(
   (response) => response.data
 );
 
@@ -103,8 +103,8 @@ const composition = (ViewComponent, ContainerComponent) =>
 
 promise.then((result) =>
   result.veryLongVariable.veryLongPropertyName > someOtherVariable
-    ? "ok"
-    : "fail"
+    ? 'ok'
+    : 'fail'
 );
 
 ================================================================================
@@ -167,33 +167,33 @@ const testResults = results.testResults.map((testResult) =>
   formatResult(testResult, formatter, reporter),
 );
 
-it("mocks regexp instances", () => {
+it('mocks regexp instances', () => {
   expect(() =>
     moduleMocker.generateFromMetadata(moduleMocker.getMetadata(/a/)),
   ).not.toThrow();
 });
 
-expect(() => asyncRequest({ url: "/test-endpoint" })).toThrowError(
+expect(() => asyncRequest({ url: '/test-endpoint' })).toThrowError(
   /Required parameter/,
 );
 
 expect(() =>
-  asyncRequest({ url: "/test-endpoint-but-with-a-long-url" }),
+  asyncRequest({ url: '/test-endpoint-but-with-a-long-url' }),
 ).toThrowError(/Required parameter/);
 
 expect(() =>
-  asyncRequest({ url: "/test-endpoint-but-with-a-suuuuuuuuper-long-url" }),
+  asyncRequest({ url: '/test-endpoint-but-with-a-suuuuuuuuper-long-url' }),
 ).toThrowError(/Required parameter/);
 
 expect(() =>
-  asyncRequest({ type: "foo", url: "/test-endpoint" }),
+  asyncRequest({ type: 'foo', url: '/test-endpoint' }),
 ).not.toThrowError();
 
 expect(() =>
-  asyncRequest({ type: "foo", url: "/test-endpoint-but-with-a-long-url" }),
+  asyncRequest({ type: 'foo', url: '/test-endpoint-but-with-a-long-url' }),
 ).not.toThrowError();
 
-const a = Observable.fromPromise(axiosInstance.post("/carts/mine")).map(
+const a = Observable.fromPromise(axiosInstance.post('/carts/mine')).map(
   (response) => response.data,
 );
 
@@ -214,8 +214,8 @@ const composition = (ViewComponent, ContainerComponent) =>
 
 promise.then((result) =>
   result.veryLongVariable.veryLongPropertyName > someOtherVariable
-    ? "ok"
-    : "fail",
+    ? 'ok'
+    : 'fail',
 );
 
 ================================================================================
@@ -278,33 +278,33 @@ const testResults = results.testResults.map((testResult) =>
   formatResult(testResult, formatter, reporter)
 );
 
-it("mocks regexp instances", () => {
+it('mocks regexp instances', () => {
   expect(() =>
     moduleMocker.generateFromMetadata(moduleMocker.getMetadata(/a/))
   ).not.toThrow();
 });
 
-expect(() => asyncRequest({ url: "/test-endpoint" })).toThrowError(
+expect(() => asyncRequest({ url: '/test-endpoint' })).toThrowError(
   /Required parameter/
 );
 
 expect(() =>
-  asyncRequest({ url: "/test-endpoint-but-with-a-long-url" })
+  asyncRequest({ url: '/test-endpoint-but-with-a-long-url' })
 ).toThrowError(/Required parameter/);
 
 expect(() =>
-  asyncRequest({ url: "/test-endpoint-but-with-a-suuuuuuuuper-long-url" })
+  asyncRequest({ url: '/test-endpoint-but-with-a-suuuuuuuuper-long-url' })
 ).toThrowError(/Required parameter/);
 
 expect(() =>
-  asyncRequest({ type: "foo", url: "/test-endpoint" })
+  asyncRequest({ type: 'foo', url: '/test-endpoint' })
 ).not.toThrowError();
 
 expect(() =>
-  asyncRequest({ type: "foo", url: "/test-endpoint-but-with-a-long-url" })
+  asyncRequest({ type: 'foo', url: '/test-endpoint-but-with-a-long-url' })
 ).not.toThrowError();
 
-const a = Observable.fromPromise(axiosInstance.post("/carts/mine")).map(
+const a = Observable.fromPromise(axiosInstance.post('/carts/mine')).map(
   (response) => response.data
 );
 
@@ -325,8 +325,8 @@ const composition = (ViewComponent, ContainerComponent) =>
 
 promise.then((result) =>
   result.veryLongVariable.veryLongPropertyName > someOtherVariable
-    ? "ok"
-    : "fail"
+    ? 'ok'
+    : 'fail'
 );
 
 ================================================================================

tests/arrows/__snapshots__/jsfmt.spec.js.snap

@@ -681,7 +681,7 @@ function render() {
 }
 
 jest.mock(
-  "../SearchSource",
+  '../SearchSource',
   () =>
     class {
       findMatchingTests(pattern) {
@@ -1478,7 +1478,7 @@ function render() {
 }
 
 jest.mock(
-  "../SearchSource",
+  '../SearchSource',
   () =>
     class {
       findMatchingTests(pattern) {
@@ -1849,11 +1849,11 @@ export const bem = (block) =>
      */
     (modifier) =>
       [
-        ".",
+        '.',
         css(block),
-        element ? \`__\${css(element)}\` : "",
-        modifier ? \`--\${css(modifier)}\` : "",
-      ].join("");
+        element ? \`__\${css(element)}\` : '',
+        modifier ? \`--\${css(modifier)}\` : '',
+      ].join('');
 
 <FlatList
   renderItem={(
@@ -1922,11 +1922,11 @@ export const bem = block =>
      */
     modifier =>
       [
-        ".",
+        '.',
         css(block),
-        element ? \`__\${css(element)}\` : "",
-        modifier ? \`--\${css(modifier)}\` : "",
-      ].join("");
+        element ? \`__\${css(element)}\` : '',
+        modifier ? \`--\${css(modifier)}\` : '',
+      ].join('');
 
 <FlatList
   renderItem={(
@@ -2082,10 +2082,10 @@ const foo = () => {
 =====================================output=====================================
 const foo = () => {
   expect(arg1, arg2, arg3).toEqual({
-    message: "test",
-    messageType: "SMS",
-    status: "Unknown",
-    created: "11/01/2017 13:36",
+    message: 'test',
+    messageType: 'SMS',
+    status: 'Unknown',
+    created: '11/01/2017 13:36',
   });
 };
 
@@ -2106,10 +2106,10 @@ const foo = () => {
 =====================================output=====================================
 const foo = () => {
   expect(arg1, arg2, arg3).toEqual({
-    message: "test",
-    messageType: "SMS",
-    status: "Unknown",
-    created: "11/01/2017 13:36",
+    message: 'test',
+    messageType: 'SMS',
+    status: 'Unknown',
+    created: '11/01/2017 13:36',
   });
 };
 

tests/arrows_bind/__snapshots__/jsfmt.spec.js.snap

@@ -11,7 +11,7 @@ a => ({}::b()\`\`[''].c++ && 0 ? 0 : 0);
 a::(b => c);
 
 =====================================output=====================================
-(a) => ({}::b()\`\`[""].c++ && 0 ? 0 : 0);
+(a) => ({}::b()\`\`[''].c++ && 0 ? 0 : 0);
 ((a) => b)::c;
 a::((b) => c);
 

tests/assignment/__snapshots__/jsfmt.spec.js.snap

@@ -61,7 +61,7 @@ const {
   accessibilityModule: FooAccessibilityModule4,
 } = foo || {};
 
-({ prop: toAssign = "default" } = { prop: "propval" });
+({ prop: toAssign = 'default' } = { prop: 'propval' });
 
 ================================================================================
 `;