[New]jsx-newline: Enforce a new line after jsx elements and expressions

CHANGELOG.md

@@ -7,8 +7,10 @@ This change log adheres to standards from [Keep a CHANGELOG](http://keepachangel
 
 ### Added
 * [`jsx-key`]: added `checkKeyMustBeforeSpread` option for new jsx transform ([#2835][] @morlay)
+* [`jsx-newline`]: add new rule ([#2693][] @jzabala)
 
 [#2835]: https://github.com/yannickcr/eslint-plugin-react/pull/2835
+[#2693]: https://github.com/yannickcr/eslint-plugin-react/pull/2693
 
 ## [7.21.5] - 2020.10.19
 
@@ -3216,3 +3218,4 @@ If you're still not using React 15 you can keep the old behavior by setting the
 [`jsx-no-script-url`]: docs/rules/jsx-no-script-url.md
 [`no-adjacent-inline-elements`]: docs/rules/no-adjacent-inline-elements.md
 [`function-component-definition`]: docs/rules/function-component-definition.md
+[`jsx-newline`]: docs/rules/jsx-newline.md

README.md

@@ -172,6 +172,7 @@ Enable the rules that you would like to use.
 * [react/jsx-key](docs/rules/jsx-key.md): Report missing `key` props in iterators/collection literals
 * [react/jsx-max-depth](docs/rules/jsx-max-depth.md): Validate JSX maximum depth
 * [react/jsx-max-props-per-line](docs/rules/jsx-max-props-per-line.md): Limit maximum of props on a single line in JSX (fixable)
+* [react/jsx-newline](docs/rules/jsx-newline.md): Enforce a new line after jsx elements and expressions (fixable)
 * [react/jsx-no-bind](docs/rules/jsx-no-bind.md): Prevents usage of Function.prototype.bind and arrow functions in React component props
 * [react/jsx-no-comment-textnodes](docs/rules/jsx-no-comment-textnodes.md): Comments inside children section of tag should be placed inside braces
 * [react/jsx-no-duplicate-props](docs/rules/jsx-no-duplicate-props.md): Enforce no duplicate props

docs/rules/jsx-newline.md

@@ -0,0 +1,65 @@
+# Enforce a new line after jsx elements and expressions (react/jsx-newline)
+
+**Fixable:** This rule is automatically fixable using the `--fix` flag on the command line.
+
+## Rule Details
+
+This is a stylistic rule intended to make JSX code more readable by enforcing spaces between adjacent JSX elements and expressions.
+
+The following patterns are considered warnings:
+
+```jsx
+<div>
+  <Button>{data.label}</Button>
+  <List />
+</div>
+```
+
+```jsx
+<div>
+  <Button>{data.label}</Button>
+  {showSomething === true && <Something />}
+</div>
+```
+
+```jsx
+<div>
+  {showSomething === true && <Something />}
+  {showSomethingElse === true ? (
+    <SomethingElse />
+  ) : (
+    <ErrorMessage />
+  )}
+</div>
+```
+
+The following patterns are **not** considered warnings:
+
+```jsx
+<div>
+  <Button>{data.label}</Button>
+
+  <List />
+
+  <Button>
+    <IconPreview />
+    Button 2
+
+    <span></span>
+  </Button>
+
+  {showSomething === true && <Something />}
+
+  <Button>Button 3</Button>
+
+  {showSomethingElse === true ? (
+    <SomethingElse />
+  ) : (
+    <ErrorMessage />
+  )}
+</div>
+```
+
+## When Not To Use It
+
+You can turn this rule off if you are not concerned with spacing between your JSX elements and expressions.

index.js

@@ -31,6 +31,7 @@ const allRules = {
   'jsx-key': require('./lib/rules/jsx-key'),
   'jsx-max-depth': require('./lib/rules/jsx-max-depth'),
   'jsx-max-props-per-line': require('./lib/rules/jsx-max-props-per-line'),
+  'jsx-newline': require('./lib/rules/jsx-newline'),
   'jsx-no-bind': require('./lib/rules/jsx-no-bind'),
   'jsx-no-comment-textnodes': require('./lib/rules/jsx-no-comment-textnodes'),
   'jsx-no-duplicate-props': require('./lib/rules/jsx-no-duplicate-props'),

lib/rules/jsx-newline.js

@@ -0,0 +1,63 @@
+/**
+ * @fileoverview Enforce a new line after jsx elements and expressions.
+ * @author Johnny Zabala
+ */
+
+'use strict';
+
+const docsUrl = require('../util/docsUrl');
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+module.exports = {
+  meta: {
+    docs: {
+      description: 'Enforce a new line after jsx elements and expressions',
+      category: 'Stylistic Issues',
+      recommended: false,
+      url: docsUrl('jsx-newline')
+    },
+    fixable: 'code'
+  },
+  create(context) {
+    const jsxElementParents = new Set();
+    const sourceCode = context.getSourceCode();
+    return {
+      'Program:exit'() {
+        jsxElementParents.forEach((parent) => {
+          parent.children.forEach((element, index, elements) => {
+            if (element.type === 'JSXElement' || element.type === 'JSXExpressionContainer') {
+              const firstAdjacentSibling = elements[index + 1];
+              const secondAdjacentSibling = elements[index + 2];
+              if (
+                firstAdjacentSibling
+                && secondAdjacentSibling
+                && (firstAdjacentSibling.type === 'Literal' || firstAdjacentSibling.type === 'JSXText')
+                // Check adjacent sibling has the proper amount of newlines
+                && !/\n\s*\n/.test(firstAdjacentSibling.value)
+              ) {
+                context.report({
+                  node: secondAdjacentSibling,
+                  message: 'JSX element should start in a new line',
+                  fix(fixer) {
+                    return fixer.replaceText(
+                      firstAdjacentSibling,
+                      // double the last newline.
+                      sourceCode.getText(firstAdjacentSibling)
+                        .replace(/(\n)(?!.*\1)/g, '\n\n')
+                    );
+                  }
+                });
+              }
+            }
+          });
+        });
+      },
+      ':matches(JSXElement, JSXFragment) > :matches(JSXElement, JSXExpressionContainer)': (node) => {
+        jsxElementParents.add(node.parent);
+      }
+    };
+  }
+};

tests/lib/rules/jsx-newline.js

@@ -0,0 +1,231 @@
+/**
+ * @fileoverview Enforce a new line after jsx elements and expressions
+ * @author Johnny Zabala
+ */
+
+'use strict';
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const RuleTester = require('eslint').RuleTester;
+const rule = require('../../../lib/rules/jsx-newline');
+const parsers = require('../../helpers/parsers');
+
+const parserOptions = {
+  ecmaVersion: 2018,
+  sourceType: 'module',
+  ecmaFeatures: {
+    jsx: true
+  }
+};
+
+// ------------------------------------------------------------------------------
+// Tests
+// ------------------------------------------------------------------------------
+
+const tests = {
+  valid: [
+    `
+    <div>
+      <Button>{data.label}</Button>
+
+      <List />
+
+      <Button>
+        <IconPreview />
+        Button 2
+
+        <span></span>
+      </Button>
+
+      {showSomething === true && <Something />}
+
+      <Button>Button 3</Button>
+
+      {showSomethingElse === true ? (
+        <SomethingElse />
+      ) : (
+        <ErrorMessage />
+      )}
+    </div>
+    `
+  ],
+  invalid: [
+    {
+      code: `
+        <div>
+          <Button>{data.label}</Button>
+          <List />
+        </div>
+      `,
+      output: `
+        <div>
+          <Button>{data.label}</Button>
+
+          <List />
+        </div>
+      `,
+      errors: [{
+        message: 'JSX element should start in a new line'
+      }]
+    },
+    {
+      code: `
+        <div>
+          <Button>{data.label}</Button>
+          {showSomething === true && <Something />}
+        </div>
+      `,
+      output: `
+        <div>
+          <Button>{data.label}</Button>
+
+          {showSomething === true && <Something />}
+        </div>
+      `,
+      errors: [{
+        message: 'JSX element should start in a new line'
+      }]
+    },
+    {
+      code: `
+        <div>
+          {showSomething === true && <Something />}
+          <Button>{data.label}</Button>
+        </div>
+      `,
+      output: `
+        <div>
+          {showSomething === true && <Something />}
+
+          <Button>{data.label}</Button>
+        </div>
+      `,
+      errors: [{
+        message: 'JSX element should start in a new line'
+      }]
+    },
+    {
+      code: `
+        <div>
+          {showSomething === true && <Something />}
+          {showSomethingElse === true ? (
+            <SomethingElse />
+          ) : (
+            <ErrorMessage />
+          )}
+        </div>
+      `,
+      output: `
+        <div>
+          {showSomething === true && <Something />}
+
+          {showSomethingElse === true ? (
+            <SomethingElse />
+          ) : (
+            <ErrorMessage />
+          )}
+        </div>
+      `,
+      errors: [{
+        message: 'JSX element should start in a new line'
+      }]
+    },
+    {
+      code: `
+        <div>
+          <div>
+            <button></button>
+            <button></button>
+          </div>
+          <div>
+            <span></span>
+            <span></span>
+          </div>
+        </div>
+      `,
+      output: `
+        <div>
+          <div>
+            <button></button>
+
+            <button></button>
+          </div>
+
+          <div>
+            <span></span>
+
+            <span></span>
+          </div>
+        </div>
+      `,
+      errors: [
+        {message: 'JSX element should start in a new line'},
+        {message: 'JSX element should start in a new line'},
+        {message: 'JSX element should start in a new line'}
+      ]
+    }
+  ]
+};
+
+const advanceFeatTest = {
+  valid: [
+    {
+      code: `
+        <>
+          <Button>{data.label}</Button>
+          Test
+
+          <span>Should be in new line</span>
+        </>
+      `
+    }
+  ],
+  invalid: [
+    {
+      code: `
+        <>
+          <Button>{data.label}</Button>
+          Test
+          <span>Should be in new line</span>
+        </>
+      `,
+      output: `
+        <>
+          <Button>{data.label}</Button>
+          Test
+
+          <span>Should be in new line</span>
+        </>
+      `,
+      errors: [
+        {message: 'JSX element should start in a new line'}
+      ]
+    }
+  ]
+};
+
+// Run tests with default parser
+new RuleTester({parserOptions}).run('jsx-newline', rule, tests);
+
+// Run tests with babel parser
+let ruleTester = new RuleTester({parserOptions, parser: parsers.BABEL_ESLINT});
+ruleTester.run('jsx-newline', rule, tests);
+ruleTester.run('jsx-newline', rule, advanceFeatTest);
+
+// Run tests with typescript parser
+ruleTester = new RuleTester({parserOptions, parser: parsers.TYPESCRIPT_ESLINT});
+ruleTester.run('jsx-newline', rule, tests);
+ruleTester.run('jsx-newline', rule, advanceFeatTest);
+
+ruleTester = new RuleTester({parserOptions, parser: parsers['@TYPESCRIPT_ESLINT']});
+ruleTester.run('jsx-newline', rule, {
+  valid: parsers.TS(tests.valid),
+  invalid: parsers.TS(tests.invalid)
+});
+ruleTester.run('jsx-newline', rule, {
+  valid: parsers.TS(advanceFeatTest.valid),
+  invalid: parsers.TS(advanceFeatTest.invalid)
+});