prefer-array-index-of: Prefer .lastIndexOf() over `.findLastIndex…

…()` (#1896)

docs/rules/prefer-array-index-of.md

@@ -1,4 +1,4 @@
-# Prefer `Array#indexOf()` over `Array#findIndex()` when looking for the index of an item
+# Prefer `Array#{indexOf,lastIndexOf}()` over `Array#{findIndex,findLastIndex}()` when looking for the index of an item
 
 <!-- Do not manually modify RULE_NOTICE part. Run: `npm run generate-rule-notices` -->
 <!-- RULE_NOTICE -->
@@ -7,7 +7,7 @@
 🔧💡 *This rule is [auto-fixable](https://eslint.org/docs/user-guide/command-line-interface#fixing-problems) and provides [suggestions](https://eslint.org/docs/developer-guide/working-with-rules#providing-suggestions).*
 <!-- /RULE_NOTICE -->
 
-[`Array#findIndex()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex) is intended for more complex needs. If you are just looking for the index where the given item is present, then the code can be simplified to use [`Array#indexOf()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf). This applies to any search with a literal, a variable, or any expression that doesn't have any explicit side effects. However, if the expression you are looking for relies on an item related to the function (its arguments, the function self, etc.), the case is still valid.
+[`Array#findIndex()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex) and [`Array#findLastIndex()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findLastIndex) are intended for more complex needs. If you are just looking for the index where the given item is present, then the code can be simplified to use [`Array#indexOf()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf) or [`Array#lastIndexOf()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/lastIndexOf) . This applies to any search with a literal, a variable, or any expression that doesn't have any explicit side effects. However, if the expression you are looking for relies on an item related to the function (its arguments, the function self, etc.), the case is still valid.
 
 This rule is fixable, unless the search expression has side effects.
 
@@ -27,6 +27,20 @@ const index = foo.findIndex(x => {
 });
 ```
 
+```js
+const index = foo.findLastIndex(x => x === 'foo');
+```
+
+```js
+const index = foo.findLastIndex(x => 'foo' === x);
+```
+
+```js
+const index = foo.findLastIndex(x => {
+	return x === 'foo';
+});
+```
+
 ## Pass
 
 ```js
@@ -63,3 +77,38 @@ const index = foo.findIndex(x => {
 	return x === bar;
 });
 ```
+
+```js
+const index = foo.lastIndexOf('foo');
+```
+
+```js
+const index = foo.findLastIndex(x => x == undefined);
+```
+
+```js
+const index = foo.findLastIndex(x => x !== 'foo');
+```
+
+```js
+const index = foo.findLastIndex((x, index) => x === index);
+```
+
+```js
+const index = foo.findLastIndex(x => (x === 'foo') && isValid());
+```
+
+```js
+const index = foo.findLastIndex(x => y === 'foo');
+```
+
+```js
+const index = foo.findLastIndex(x => y.x === 'foo');
+```
+
+```js
+const index = foo.findLastIndex(x => {
+	const bar = getBar();
+	return x === bar;
+});
+```

readme.md

@@ -108,7 +108,7 @@ Each rule has emojis denoting:
 | [prefer-array-find](docs/rules/prefer-array-find.md) | Prefer `.find(…)` over the first element from `.filter(…)`. | ✅ | 🔧 | 💡 |
 | [prefer-array-flat](docs/rules/prefer-array-flat.md) | Prefer `Array#flat()` over legacy techniques to flatten arrays. | ✅ | 🔧 |  |
 | [prefer-array-flat-map](docs/rules/prefer-array-flat-map.md) | Prefer `.flatMap(…)` over `.map(…).flat()`. | ✅ | 🔧 |  |
-| [prefer-array-index-of](docs/rules/prefer-array-index-of.md) | Prefer `Array#indexOf()` over `Array#findIndex()` when looking for the index of an item. | ✅ | 🔧 | 💡 |
+| [prefer-array-index-of](docs/rules/prefer-array-index-of.md) | Prefer `Array#{indexOf,lastIndexOf}()` over `Array#{findIndex,findLastIndex}()` when looking for the index of an item. | ✅ | 🔧 | 💡 |
 | [prefer-array-some](docs/rules/prefer-array-some.md) | Prefer `.some(…)` over `.filter(…).length` check and `.{find,findLast}(…)`. | ✅ | 🔧 | 💡 |
 | [prefer-at](docs/rules/prefer-at.md) | Prefer `.at()` method for index access and `String#charAt()`. |  | 🔧 | 💡 |
 | [prefer-code-point](docs/rules/prefer-code-point.md) | Prefer `String#codePointAt(…)` over `String#charCodeAt(…)` and `String.fromCodePoint(…)` over `String.fromCharCode(…)`. | ✅ |  | 💡 |

rules/prefer-array-index-of.js

@@ -1,21 +1,32 @@
 'use strict';
 const simpleArraySearchRule = require('./shared/simple-array-search-rule.js');
 
-const {messages, createListeners} = simpleArraySearchRule({
+const indexOfOverFindIndexRule = simpleArraySearchRule({
 	method: 'findIndex',
 	replacement: 'indexOf',
 });
 
+const lastIndexOfOverFindLastIndexRule = simpleArraySearchRule({
+	method: 'findLastIndex',
+	replacement: 'lastIndexOf',
+});
+
 /** @type {import('eslint').Rule.RuleModule} */
 module.exports = {
-	create: context => createListeners(context),
+	create: context => ({
+		...indexOfOverFindIndexRule.createListeners(context),
+		...lastIndexOfOverFindLastIndexRule.createListeners(context),
+	}),
 	meta: {
 		type: 'suggestion',
 		docs: {
-			description: 'Prefer `Array#indexOf()` over `Array#findIndex()` when looking for the index of an item.',
+			description: 'Prefer `Array#{indexOf,lastIndexOf}()` over `Array#{findIndex,findLastIndex}()` when looking for the index of an item.',
 		},
 		fixable: 'code',
 		hasSuggestions: true,
-		messages,
+		messages: {
+			...indexOfOverFindIndexRule.messages,
+			...lastIndexOfOverFindLastIndexRule.messages,
+		},
 	},
 };

test/prefer-array-index-of.mjs

@@ -1,12 +1,20 @@
 import {getTester} from './utils/test.mjs';
-import tests from './shared/simple-array-search-rule-tests.mjs';
+import createSimpleArraySearchRuleTestFixtures from './shared/simple-array-search-rule-tests.mjs';
 
 const {test} = getTester(import.meta);
 
-const {snapshot, typescript} = tests({
+const indexOfOverFindIndexFixtures = createSimpleArraySearchRuleTestFixtures({
 	method: 'findIndex',
 	replacement: 'indexOf',
 });
 
-test.snapshot(snapshot);
-test.typescript(typescript);
+test.snapshot(indexOfOverFindIndexFixtures.snapshot);
+test.typescript(indexOfOverFindIndexFixtures.typescript);
+
+const lastIndexOfOverFindLastIndexFixtures = createSimpleArraySearchRuleTestFixtures({
+	method: 'findLastIndex',
+	replacement: 'lastIndexOf',
+});
+
+test.snapshot(lastIndexOfOverFindLastIndexFixtures.snapshot);
+test.typescript(lastIndexOfOverFindLastIndexFixtures.typescript);

test/shared/simple-array-search-rule-tests.mjs

@@ -19,7 +19,7 @@ function snapshotTests({method, replacement}) {
 			// Computed
 			`foo[${method}](x => x === 1)`,
 			// Not `findIndex`
-			'foo.notListedMethod(x => x === 1)',
+			`foo.not_${method}(x => x === 1)`,
 
 			// Test `callback` part
 			// Not function