[New] : Enforce no unused React elements

README.md

@@ -132,6 +132,7 @@ Enable the rules that you would like to use.
 * [react/no-unescaped-entities](docs/rules/no-unescaped-entities.md): Detect unescaped HTML entities, which might represent malformed tags
 * [react/no-unknown-property](docs/rules/no-unknown-property.md): Prevent usage of unknown DOM property (fixable)
 * [react/no-unsafe](docs/rules/no-unsafe.md): Prevent usage of unsafe lifecycle methods
+* [react/no-unused-elements](docs/rules/no-unused-elements.md): Disallow unused React elements
 * [react/no-unused-prop-types](docs/rules/no-unused-prop-types.md): Prevent definitions of unused prop types
 * [react/no-unused-state](docs/rules/no-unused-state.md): Prevent definition of unused state fields
 * [react/no-will-update-set-state](docs/rules/no-will-update-set-state.md): Prevent usage of setState in componentWillUpdate
@@ -179,7 +180,7 @@ Enable the rules that you would like to use.
 * [react/jsx-no-duplicate-props](docs/rules/jsx-no-duplicate-props.md): Enforce no duplicate props
 * [react/jsx-no-literals](docs/rules/jsx-no-literals.md): Prevent using string literals in React component definition
 * [react/jsx-no-script-url](docs/rules/jsx-no-script-url.md): Forbid `javascript:` URLs
-* [react/jsx-no-target-blank](docs/rules/jsx-no-target-blank.md): Forbid `target="_blank"` attribute without `rel="noreferrer"`
+* [react/jsx-no-target-blank](docs/rules/jsx-no-target-blank.md): Forbid `target="_blank"` attribute without `rel="noreferrer"` (fixable)
 * [react/jsx-no-undef](docs/rules/jsx-no-undef.md): Disallow undeclared variables in JSX
 * [react/jsx-no-useless-fragment](docs/rules/jsx-no-useless-fragment.md): Disallow unnecessary fragments (fixable)
 * [react/jsx-one-expression-per-line](docs/rules/jsx-one-expression-per-line.md): Limit to one expression per line in JSX (fixable)

docs/rules/no-unused-elements.md

@@ -0,0 +1,25 @@
+# Disallow unused React elements  (react/no-unused-elements)
+
+An unused React element indicates a logic error.
+
+## Rule Details
+
+Examples of **incorrect** code for this rule:
+
+```jsx
+<div />;
+```
+
+```js
+React.createElement('div');
+```
+
+Examples of **correct** code for this rule:
+
+```js
+return <div />;
+```
+
+```js
+const partial = <div />;
+```

index.js

@@ -76,6 +76,7 @@ const allRules = {
   'no-unescaped-entities': require('./lib/rules/no-unescaped-entities'),
   'no-unknown-property': require('./lib/rules/no-unknown-property'),
   'no-unsafe': require('./lib/rules/no-unsafe'),
+  'no-unused-elements': require('./lib/rules/no-unused-elements'),
   'no-unused-prop-types': require('./lib/rules/no-unused-prop-types'),
   'no-unused-state': require('./lib/rules/no-unused-state'),
   'no-will-update-set-state': require('./lib/rules/no-will-update-set-state'),

lib/rules/no-unused-elements.js

@@ -0,0 +1,53 @@
+/**
+ * @fileoverview Disallow unused React elements
+ * @author Duncan Beevers
+ */
+
+'use strict';
+
+const Components = require('../util/Components');
+const docsUrl = require('../util/docsUrl');
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+const NO_UNUSED_ELEMENTS_MESSAGE = 'noUnusedElements';
+
+module.exports = {
+  meta: {
+    docs: {
+      description: 'Disallow unused React elements',
+      category: 'Best Practices',
+      recommended: false,
+      url: docsUrl('no-unused-elements')
+    },
+    messages: {
+      [NO_UNUSED_ELEMENTS_MESSAGE]: 'Unused React element'
+    },
+    schema: [{
+      type: 'object',
+      additionalProperties: false
+    }]
+  },
+
+  create: Components.detect((context, components, utils) => ({
+    JSXElement(node) {
+      if (node.parent.type === 'ExpressionStatement') {
+        context.report({
+          node,
+          messageId: NO_UNUSED_ELEMENTS_MESSAGE
+        });
+      }
+    },
+    CallExpression(node) {
+      if (utils.isCreateElement(node) && node.parent.type === 'ExpressionStatement') {
+        context.report({
+          node,
+          messageId: NO_UNUSED_ELEMENTS_MESSAGE
+        });
+      }
+    }
+  })
+  )
+};

tests/lib/rules/no-unused-elements.js

@@ -0,0 +1,63 @@
+/**
+ * @fileoverview Disallow unused React elements
+ * @author Duncan Beevers
+ */
+
+'use strict';
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const RuleTester = require('eslint').RuleTester;
+const rule = require('../../../lib/rules/no-unused-elements');
+
+// ------------------------------------------------------------------------------
+// Tests
+// ------------------------------------------------------------------------------
+
+const ruleTester = new RuleTester({
+  parserOptions: {
+    ecmaVersion: 2018,
+    sourceType: 'module',
+    ecmaFeatures: {
+      jsx: true
+    }
+  }
+});
+
+const tests = {
+  valid: [
+    {
+      code: 'const partial = <div />'
+    },
+    {
+      code: '() => <div />'
+    },
+    {
+      code: 'const partial = React.createElement(\'div\', {}, \'\')'
+    }
+  ],
+  invalid: [
+    {
+      code: '<div />',
+      errors: [{
+        message: 'Unused React element'
+      }]
+    },
+    {
+      code: 'React.createElement(\'div\', {}, \'\')',
+      errors: [{
+        message: 'Unused React element'
+      }]
+    },
+    {
+      code: 'if (condition) { <div /> }',
+      errors: [{
+        message: 'Unused React element'
+      }]
+    }
+  ]
+};
+
+ruleTester.run('no-unused-elements', rule, tests);