[Refactor] use fromEntries, flatMap, etc; better use iteration methods

Author: ljharb

__mocks__/genInteractives.js

@@ -4,6 +4,8 @@
 
 import { dom, roles } from 'aria-query';
 import includes from 'array-includes';
+import fromEntries from 'object.fromentries';
+
 import JSXAttributeMock from './JSXAttributeMock';
 import JSXElementMock from './JSXElementMock';
 
@@ -115,13 +117,7 @@ const nonInteractiveElementsMap: {[string]: Array<{[string]: string}>} = {
   ul: [],
 };
 
-const indeterminantInteractiveElementsMap = domElements.reduce(
-  (accumulator: { [key: string]: Array<any> }, name: string): { [key: string]: Array<any> } => ({
-    ...accumulator,
-    [name]: [],
-  }),
-  {},
-);
+const indeterminantInteractiveElementsMap: { [key: string]: Array<any> } = fromEntries(domElements.map((name: string) => [name, []]));
 
 Object.keys(interactiveElementsMap)
   .concat(Object.keys(nonInteractiveElementsMap))
@@ -138,22 +134,25 @@ const interactiveRoles = []
     // aria-activedescendant, thus in practice we treat it as a widget.
     'toolbar',
   )
-  .filter((role) => !roles.get(role).abstract)
-  .filter((role) => roles.get(role).superClass.some((klasses) => includes(klasses, 'widget')));
+  .filter((role) => (
+    !roles.get(role).abstract
+    && roles.get(role).superClass.some((klasses) => includes(klasses, 'widget'))
+  ));
 
 const nonInteractiveRoles = roleNames
-  .filter((role) => !roles.get(role).abstract)
-  .filter((role) => !roles.get(role).superClass.some((klasses) => includes(klasses, 'widget')))
-  // 'toolbar' does not descend from widget, but it does support
-  // aria-activedescendant, thus in practice we treat it as a widget.
-  .filter((role) => !includes(['toolbar'], role));
+  .filter((role) => (
+    !roles.get(role).abstract
+    && !roles.get(role).superClass.some((klasses) => includes(klasses, 'widget'))
+
+    // 'toolbar' does not descend from widget, but it does support
+    // aria-activedescendant, thus in practice we treat it as a widget.
+    && !includes(['toolbar'], role)
+  ));
 
 export function genElementSymbol(openingElement: Object): string {
   return (
     openingElement.name.name + (openingElement.attributes.length > 0
-      ? `${openingElement.attributes
-        .map((attr) => `[${attr.name.name}="${attr.value.value}"]`)
-        .join('')}`
+      ? `${openingElement.attributes.map((attr) => `[${attr.name.name}="${attr.value.value}"]`).join('')}`
       : ''
     )
   );
@@ -172,7 +171,7 @@ export function genInteractiveElements(): Array<JSXElementMockType> {
 }
 
 export function genInteractiveRoleElements(): Array<JSXElementMockType> {
-  return [...interactiveRoles, 'button article', 'fakerole button article'].map((value): JSXElementMockType => JSXElementMock(
+  return interactiveRoles.concat('button article', 'fakerole button article').map((value): JSXElementMockType => JSXElementMock(
     'div',
     [JSXAttributeMock('role', value)],
   ));

__tests__/__util__/ruleOptionsMapperFactory.js

@@ -2,6 +2,10 @@
  * @flow
  */
 
+import entries from 'object.entries';
+import flatMap from 'array.prototype.flatmap';
+import fromEntries from 'object.fromentries';
+
 type ESLintTestRunnerTestCase = {
   code: string,
   errors: ?Array<{ message: string, type: string }>,
@@ -21,10 +25,7 @@ export default function ruleOptionsMapperFactory(ruleOptions: Array<mixed> = [])
       code,
       errors,
       // Flatten the array of objects in an array of one object.
-      options: (options || []).concat(ruleOptions).reduce((acc, item) => [{
-        ...acc[0],
-        ...item,
-      }], [{}]),
+      options: [fromEntries(flatMap((options || []).concat(ruleOptions), (item) => entries(item)))],
       parserOptions,
       settings,
     };

__tests__/src/rules/aria-unsupported-elements-test.js

@@ -50,7 +50,7 @@ const ariaValidityTests = domElements.map((element) => {
 
 // Generate invalid test cases.
 const invalidRoleValidityTests = domElements
-  .filter((element) => Boolean(dom.get(element).reserved))
+  .filter((element) => dom.get(element).reserved)
   .map((reservedElem) => ({
     code: `<${reservedElem} role {...props} />`,
     errors: [errorMessage('role')],
@@ -61,7 +61,7 @@ const invalidRoleValidityTests = domElements
   });
 
 const invalidAriaValidityTests = domElements
-  .filter((element) => Boolean(dom.get(element).reserved))
+  .filter((element) => dom.get(element).reserved)
   .map((reservedElem) => ({
     code: `<${reservedElem} aria-hidden aria-role="none" {...props} />`,
     errors: [errorMessage('aria-hidden')],

package.json

@@ -72,6 +72,7 @@
     "@babel/runtime": "^7.20.7",
     "aria-query": "^5.1.3",
     "array-includes": "^3.1.6",
+    "array.prototype.flatmap": "^1.3.1",
     "ast-types-flow": "^0.0.7",
     "axe-core": "^4.6.2",
     "axobject-query": "^3.1.1",
@@ -81,6 +82,8 @@
     "jsx-ast-utils": "^3.3.3",
     "language-tags": "=1.0.5",
     "minimatch": "^3.1.2",
+    "object.entries": "^1.1.6",
+    "object.fromentries": "^2.0.6",
     "semver": "^6.3.0"
   },
   "peerDependencies": {

src/rules/alt-text.js

@@ -12,6 +12,8 @@ import {
   getPropValue,
   getLiteralPropValue,
 } from 'jsx-ast-utils';
+import flatMap from 'array.prototype.flatmap';
+
 import { generateObjSchema, arraySchema } from '../util/schemas';
 import getElementType from '../util/getElementType';
 import hasAccessibleChild from '../util/hasAccessibleChild';
@@ -204,12 +206,10 @@ export default {
     // Elements to validate for alt text.
     const elementOptions = options.elements || DEFAULT_ELEMENTS;
     // Get custom components for just the elements that will be tested.
-    const customComponents = elementOptions
-      .map((element) => options[element])
-      .reduce(
-        (components, customComponentsForElement) => components.concat(customComponentsForElement || []),
-        [],
-      );
+    const customComponents = flatMap(
+      elementOptions,
+      (element) => options[element],
+    );
     const typesToValidate = new Set(
       [].concat(
         customComponents,

src/rules/anchor-is-valid.js

@@ -64,16 +64,12 @@ export default ({
 
         const propOptions = options.specialLink || [];
         const propsToValidate = ['href'].concat(propOptions);
-        const values = propsToValidate
-          .map((prop) => getProp(node.attributes, prop))
-          .map((prop) => getPropValue(prop));
+        const values = propsToValidate.map((prop) => getPropValue(getProp(node.attributes, prop)));
         // Checks if any actual or custom href prop is provided.
-        const hasAnyHref = values
-          .filter((value) => value === undefined || value === null).length !== values.length;
+        const hasAnyHref = values.some((value) => value != null);
         // Need to check for spread operator as props can be spread onto the element
         // leading to an incorrect validation error.
-        const hasSpreadOperator = attributes
-          .filter((prop) => prop.type === 'JSXSpreadAttribute').length > 0;
+        const hasSpreadOperator = attributes.some((prop) => prop.type === 'JSXSpreadAttribute');
         const onClick = getProp(attributes, 'onClick');
 
         // When there is no href at all, specific scenarios apply:
@@ -99,10 +95,12 @@ export default ({
 
         // Hrefs have been found, now check for validity.
         const invalidHrefValues = values
-          .filter((value) => value !== undefined && value !== null)
-          .filter((value) => (typeof value === 'string' && (
-            !value.length || value === '#' || /^\W*?javascript:/.test(value)
-          )));
+          .filter((value) => (
+            value != null
+            && (typeof value === 'string' && (
+              !value.length || value === '#' || /^\W*?javascript:/.test(value)
+            ))
+          ));
         if (invalidHrefValues.length !== 0) {
           // If an onClick is found it should be a button, otherwise it is an invalid link.
           if (onClick && activeAspects.preferButton) {

src/rules/interactive-supports-focus.js

@@ -36,9 +36,10 @@ import getTabIndex from '../util/getTabIndex';
 // ----------------------------------------------------------------------------
 
 const schema = generateObjSchema({
-  tabbable: enumArraySchema([...roles.keys()]
-    .filter((name) => !roles.get(name).abstract)
-    .filter((name) => roles.get(name).superClass.some((klasses) => includes(klasses, 'widget')))),
+  tabbable: enumArraySchema([...roles.keys()].filter((name) => (
+    !roles.get(name).abstract
+    && roles.get(name).superClass.some((klasses) => includes(klasses, 'widget'))
+  ))),
 });
 const domElements = [...dom.keys()];
 

src/rules/media-has-caption.js

@@ -10,6 +10,8 @@
 
 import type { JSXElement, JSXOpeningElement, Node } from 'ast-types-flow';
 import { getProp, getLiteralPropValue } from 'jsx-ast-utils';
+import flatMap from 'array.prototype.flatmap';
+
 import type { ESLintConfig, ESLintContext, ESLintVisitorSelectorConfig } from '../../flow/eslint';
 import { generateObjSchema, arraySchema } from '../util/schemas';
 import getElementType from '../util/getElementType';
@@ -26,8 +28,8 @@ const schema = generateObjSchema({
 
 const isMediaType = (context, type) => {
   const options = context.options[0] || {};
-  return MEDIA_TYPES.map((mediaType) => options[mediaType])
-    .reduce((types, customComponent) => types.concat(customComponent), MEDIA_TYPES)
+  return MEDIA_TYPES
+    .concat(flatMap(MEDIA_TYPES, (mediaType) => options[mediaType]))
     .some((typeToCheck) => typeToCheck === type);
 };
 

src/util/getSuggestion.js

@@ -1,4 +1,5 @@
 import editDistance from 'damerau-levenshtein';
+import fromEntries from 'object.fromentries';
 
 // Minimum edit distance to be considered a good suggestion.
 const THRESHOLD = 2;
@@ -8,12 +9,13 @@ const THRESHOLD = 2;
  * to return.
  */
 export default function getSuggestion(word, dictionary = [], limit = 2) {
-  const distances = dictionary.reduce((suggestions, dictionaryWord) => {
-    const distance = editDistance(word.toUpperCase(), dictionaryWord.toUpperCase());
-    const { steps } = distance;
-    suggestions[dictionaryWord] = steps; // eslint-disable-line
-    return suggestions;
-  }, {});
+  const distances = fromEntries(
+    dictionary.map((dictionaryWord) => {
+      const distance = editDistance(word.toUpperCase(), dictionaryWord.toUpperCase());
+      const { steps } = distance;
+      return [dictionaryWord, steps];
+    }),
+  );
 
   return Object.keys(distances)
     .filter((suggestion) => distances[suggestion] <= THRESHOLD)

src/util/hasAccessibleChild.js

@@ -8,10 +8,10 @@ export default function hasAccessibleChild(node: JSXElement, elementType: (JSXOp
   return node.children.some((child: Node) => {
     switch (child.type) {
       case 'Literal':
-        return Boolean(child.value);
+        return !!child.value;
       // $FlowFixMe JSXText is missing in ast-types-flow
       case 'JSXText':
-        return Boolean(child.value);
+        return !!child.value;
       case 'JSXElement':
         return !isHiddenFromScreenReader(
           elementType(child.openingElement),