[new] - Consolidate no-marquee and no-blink into no-distracting-elements rule. (#140)

This is a breaking change. Will be included in next major release!

Author: beefancohen

__tests__/src/rules/no-marquee-test.js renamed to __tests__/src/rules/no-distracting-elements-test.js

@@ -1,5 +1,5 @@
 /**
- * @fileoverview Enforce <marquee> elements are not used.
+ * @fileoverview Enforce distracting elements are not used.
  * @author Ethan Cohen
  */
 
@@ -8,7 +8,7 @@
 // -----------------------------------------------------------------------------
 
 import { RuleTester } from 'eslint';
-import rule from '../../../src/rules/no-marquee';
+import rule from '../../../src/rules/no-distracting-elements';
 
 const parserOptions = {
   ecmaVersion: 6,
@@ -23,20 +23,25 @@ const parserOptions = {
 
 const ruleTester = new RuleTester();
 
-const expectedError = {
-  message: 'Do not use <marquee> elements as they create accessibility issues and are deprecated.',
+const expectedError = element => ({
+  message: `Do not use <${element}> elements as they can create visual accessibility issues and are deprecated.`,
   type: 'JSXOpeningElement',
-};
+});
 
 ruleTester.run('no-marquee', rule, {
   valid: [
     { code: '<div />;', parserOptions },
     { code: '<Marquee />', parserOptions },
     { code: '<div marquee />', parserOptions },
+    { code: '<Blink />', parserOptions },
+    { code: '<div blink />', parserOptions },
   ],
   invalid: [
-    { code: '<marquee />', errors: [expectedError], parserOptions },
-    { code: '<marquee {...props} />', errors: [expectedError], parserOptions },
-    { code: '<marquee lang={undefined} />', errors: [expectedError], parserOptions },
+    { code: '<marquee />', errors: [expectedError('marquee')], parserOptions },
+    { code: '<marquee {...props} />', errors: [expectedError('marquee')], parserOptions },
+    { code: '<marquee lang={undefined} />', errors: [expectedError('marquee')], parserOptions },
+    { code: '<blink />', errors: [expectedError('blink')], parserOptions },
+    { code: '<blink {...props} />', errors: [expectedError('blink')], parserOptions },
+    { code: '<blink foo={undefined} />', errors: [expectedError('blink')], parserOptions },
   ],
 });

docs/rules/no-distracting-elements.md

@@ -0,0 +1,34 @@
+# no-distracting-elements
+
+Enforces that no distracting elements are used. Elements that can be visually distracting can cause accessibility issues with visually impaired users. Such elements are most likely deprecated, and should be avoided. By default, the following elements are visually distracting: `<marquee>` and `<blink>`.
+
+#### References
+1. [Deque University](https://dequeuniversity.com/rules/axe/1.1/marquee)
+2. [Deque University](https://dequeuniversity.com/rules/axe/1.1/blink)
+
+## Rule details
+
+This rule takes one optional object argument of type object:
+
+```json
+{
+    "rules": {
+        "jsx-a11y/no-distracting-elements": [ 2, {
+            "elements": [ "marquee", "blink" ],
+          }],
+    }
+}
+```
+
+For the `elements` option, these strings determine which JSX elements should be checked for usage. This shouldn't need to be configured unless you have a seriously compelling use case for these elements. You cannot add any additional elements than what is offered, as the schema is only valid with the provided enumerated list. If you have another element that you think may cause a11y issues due to visual impairment, please feel free to file an issue or send a PR!
+
+### Succeed
+```jsx
+<div />
+```
+
+### Fail
+```jsx
+<marquee />
+<blink />
+```

docs/rules/no-marquee.md

@@ -19,7 +19,7 @@ module.exports = {
     lang: require('./rules/lang'),
     'mouse-events-have-key-events': require('./rules/mouse-events-have-key-events'),
     'no-access-key': require('./rules/no-access-key'),
-    'no-marquee': require('./rules/no-marquee'),
+    'no-distracting-elements': require('./rules/no-distracting-elements'),
     'no-onchange': require('./rules/no-onchange'),
     'no-static-element-interactions': require('./rules/no-static-element-interactions'),
     'onclick-has-focus': require('./rules/onclick-has-focus'),
@@ -53,7 +53,7 @@ module.exports = {
         'jsx-a11y/label-has-for': 'error',
         'jsx-a11y/mouse-events-have-key-events': 'error',
         'jsx-a11y/no-access-key': 'error',
-        'jsx-a11y/no-marquee': 'error',
+        'jsx-a11y/no-distracting-elements': 'error',
         'jsx-a11y/no-onchange': 'error',
         'jsx-a11y/no-static-element-interactions': 'warn',
         'jsx-a11y/onclick-has-focus': 'error',

src/index.js

@@ -0,0 +1,47 @@
+/**
+ * @fileoverview Enforce distracting elements are not used.
+ * @author Ethan Cohen
+ */
+
+// ----------------------------------------------------------------------------
+// Rule Definition
+// ----------------------------------------------------------------------------
+
+import { elementType } from 'jsx-ast-utils';
+import { generateObjSchema, enumArraySchema } from '../util/schemas';
+
+const errorMessage = element =>
+  `Do not use <${element}> elements as they can create visual accessibility issues and are deprecated.`;
+
+
+const DEFAULT_ELEMENTS = [
+  'marquee',
+  'blink',
+];
+
+const schema = generateObjSchema({
+  elements: enumArraySchema(DEFAULT_ELEMENTS),
+});
+
+module.exports = {
+  meta: {
+    docs: {},
+    schema: [schema],
+  },
+
+  create: context => ({
+    JSXOpeningElement: (node) => {
+      const options = context.options[0] || {};
+      const elementOptions = options.elements || DEFAULT_ELEMENTS;
+      const type = elementType(node);
+      const distractingElement = elementOptions.find(element => type === element);
+
+      if (distractingElement) {
+        context.report({
+          node,
+          message: errorMessage(distractingElement),
+        });
+      }
+    },
+  }),
+};

src/rules/no-distracting-elements.js

@@ -1,20 +1,33 @@
+import assign from 'object-assign';
+
 /**
  * JSON schema to accept an array of unique strings
  */
- export const arraySchema = {
-   type: 'array',
-   items: {
-     type: 'string',
-   },
-   minItems: 1,
-   uniqueItems: true,
- };
+export const arraySchema = {
+  type: 'array',
+  items: {
+    type: 'string',
+  },
+  minItems: 1,
+  uniqueItems: true,
+  additionalItems: false,
+};
+
+/**
+ * JSON schema to accept an array of unique strings from an enumerated list.
+ */
+export const enumArraySchema = (enumeratedList = []) => assign({}, arraySchema, {
+  items: {
+    type: 'string',
+    enum: enumeratedList,
+  },
+});
 
 /**
  * Factory function to generate an object schema
  * with specified properties object
  */
- export const generateObjSchema = (properties = {}) => ({
-   type: 'object',
-   properties,
- });
+export const generateObjSchema = (properties = {}) => ({
+  type: 'object',
+  properties,
+});