prefer-negative-index: Support Array#at() (sindresorhus#1217)

Author: fisker

docs/rules/prefer-negative-index.md

@@ -1,23 +1,49 @@
-# Prefer negative index over `.length - index` for `{String,Array,TypedArray}#slice()` and `Array#splice()`
+# Prefer negative index over `.length - index` for `{String,Array,TypedArray}#slice()`, `Array#splice()` and `Array#at()`
 
-Prefer negative index over calculating from `.length` for [`String#slice()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice), [`Array#slice`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice), [`TypedArray#slice`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/slice) and [`Array#splice()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/splice)
+Prefer negative index over calculating from `.length` for [`String#slice()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice), [`Array#slice`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice), [`TypedArray#slice`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/slice) , [`Array#splice()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/splice) and [`Array#at()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/at)
 
 This rule is fixable.
 
 ## Fail
 
 ```js
 foo.slice(foo.length - 2, foo.length - 1);
+```
+
+```js
 foo.splice(foo.length - 1, 1);
+```
+
+```js
+foo.at(foo.length - 1);
+```
+
+```js
 Array.prototype.slice.call(foo, foo.length - 2, foo.length - 1);
+```
+
+```js
 Array.prototype.slice.apply(foo, [foo.length - 2, foo.length - 1]);
 ```
 
 ## Pass
 
 ```js
 foo.slice(-2, -1);
+```
+
+```js
 foo.splice(-1, 1);
+```
+
+```js
+foo.at(-1);
+```
+
+```js
 Array.prototype.slice.call(foo, -2, -1);
+```
+
+```js
 Array.prototype.slice.apply(foo, [-2, -1]);
 ```

readme.md

@@ -187,7 +187,7 @@ Each rule has emojis denoting:
 | [prefer-math-trunc](docs/rules/prefer-math-trunc.md) | Enforce the use of `Math.trunc` instead of bitwise operators. | ✅ | 🔧 |
 | [prefer-modern-dom-apis](docs/rules/prefer-modern-dom-apis.md) | Prefer `.before()` over `.insertBefore()`, `.replaceWith()` over `.replaceChild()`, prefer one of `.before()`, `.after()`, `.append()` or `.prepend()` over `insertAdjacentText()` and `insertAdjacentElement()`. | ✅ | 🔧 |
 | [prefer-module](docs/rules/prefer-module.md) | Prefer JavaScript modules (ESM) over CommonJS. | ✅ | 🔧 |
-| [prefer-negative-index](docs/rules/prefer-negative-index.md) | Prefer negative index over `.length - index` for `{String,Array,TypedArray}#slice()` and `Array#splice()`. | ✅ | 🔧 |
+| [prefer-negative-index](docs/rules/prefer-negative-index.md) | Prefer negative index over `.length - index` for `{String,Array,TypedArray}#slice()`, `Array#splice()` and `Array#at()`. | ✅ | 🔧 |
 | [prefer-node-protocol](docs/rules/prefer-node-protocol.md) | Prefer using the `node:` protocol when importing Node.js builtin modules. | ✅ | 🔧 |
 | [prefer-number-properties](docs/rules/prefer-number-properties.md) | Prefer `Number` static properties over global ones. | ✅ | 🔧 |
 | [prefer-optional-catch-binding](docs/rules/prefer-optional-catch-binding.md) | Prefer omitting the `catch` binding parameter. | ✅ | 🔧 |

rules/prefer-negative-index.js

@@ -42,6 +42,15 @@ const methods = new Map([
 				'Array'
 			])
 		}
+	],
+	[
+		'at',
+		{
+			argumentsIndexes: [0],
+			supportObjects: new Set([
+				'Array'
+			])
+		}
 	]
 ]);
 
@@ -255,7 +264,7 @@ module.exports = {
 	meta: {
 		type: 'suggestion',
 		docs: {
-			description: 'Prefer negative index over `.length - index` for `{String,Array,TypedArray}#slice()` and `Array#splice()`.',
+			description: 'Prefer negative index over `.length - index` for `{String,Array,TypedArray}#slice()`, `Array#splice()` and `Array#at()`.',
 			url: getDocumentationUrl(__filename)
 		},
 		fixable: 'code',

test/prefer-negative-index.mjs

@@ -355,6 +355,11 @@ test.snapshot({
 		// Foo[1] and foo["1"]
 		'foo[1].slice(foo["1"].length - 1)',
 		// Foo['bar'] & foo["bar"]
-		'foo[\'bar\'].slice(foo["bar"].length - 1)'
+		'foo[\'bar\'].slice(foo["bar"].length - 1)',
+		outdent`
+			foo.at(foo.length - 1);
+			Array.prototype.at.call(foo, foo.length - 2);
+			Array.prototype.at.apply(foo, [foo.length - 3]);
+		`
 	]
 });

test/snapshots/prefer-negative-index.mjs.md

@@ -99,3 +99,43 @@ Generated by [AVA](https://avajs.dev).
     > 1 | foo['bar'].slice(foo["bar"].length - 1)␊
         | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Prefer negative index over length minus index for \`slice\`.␊
     `
+
+## Invalid #7
+      1 | foo.at(foo.length - 1);
+      2 | Array.prototype.at.call(foo, foo.length - 2);
+      3 | Array.prototype.at.apply(foo, [foo.length - 3]);
+
+> Output
+
+    `␊
+      1 | foo.at(- 1);␊
+      2 | Array.prototype.at.call(foo, - 2);␊
+      3 | Array.prototype.at.apply(foo, [- 3]);␊
+    `
+
+> Error 1/3
+
+    `␊
+    > 1 | foo.at(foo.length - 1);␊
+        | ^^^^^^^^^^^^^^^^^^^^^^ Prefer negative index over length minus index for \`at\`.␊
+      2 | Array.prototype.at.call(foo, foo.length - 2);␊
+      3 | Array.prototype.at.apply(foo, [foo.length - 3]);␊
+    `
+
+> Error 2/3
+
+    `␊
+      1 | foo.at(foo.length - 1);␊
+    > 2 | Array.prototype.at.call(foo, foo.length - 2);␊
+        | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Prefer negative index over length minus index for \`at\`.␊
+      3 | Array.prototype.at.apply(foo, [foo.length - 3]);␊
+    `
+
+> Error 3/3
+
+    `␊
+      1 | foo.at(foo.length - 1);␊
+      2 | Array.prototype.at.call(foo, foo.length - 2);␊
+    > 3 | Array.prototype.at.apply(foo, [foo.length - 3]);␊
+        | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Prefer negative index over length minus index for \`at\`.␊
+    `