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fiskerfisker
authoredFeb 1, 2023
prefer-spread: Forbid use of Array#toSpliced() to copy array (#2034)
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v58.0.0v46.0.0
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‎docs/rules/prefer-spread.md

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Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
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# Prefer the spread operator over `Array.from(…)`, `Array#concat(…)`, `Array#slice()` and `String#split('')`
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# Prefer the spread operator over `Array.from(…)`, `Array#concat(…)`, `Array#{slice,toSpliced}()` and `String#split('')`
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💼 This rule is enabled in the ✅ `recommended` [config](https://github.com/sindresorhus/eslint-plugin-unicorn#preset-configs).
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@@ -25,6 +25,10 @@ Enforces the use of [the spread operator (`...`)](https://developer.mozilla.org/
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Variables named `arrayBuffer`, `blob`, `buffer`, `file`, and `this` are ignored.
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- `Array#toSpliced()`
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Shallow copy an `Array`.
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- `String#split('')`
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Split a string into an array of characters.
@@ -47,6 +51,14 @@ const array = array1.concat(array2);
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const copy = array.slice();
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```
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```js
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const copy = array.slice(0);
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```
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```js
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const copy = array.toSpliced();
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```
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```js
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const characters = string.split('');
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```

‎readme.md

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@@ -145,7 +145,7 @@ If you don't use the preset, ensure you use the same `env` and `parserOptions` c
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| [prefer-regexp-test](docs/rules/prefer-regexp-test.md) | Prefer `RegExp#test()` over `String#match()` and `RegExp#exec()`. | ✅ | 🔧 | 💡 |
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| [prefer-set-has](docs/rules/prefer-set-has.md) | Prefer `Set#has()` over `Array#includes()` when checking for existence or non-existence. | ✅ | 🔧 | 💡 |
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| [prefer-set-size](docs/rules/prefer-set-size.md) | Prefer using `Set#size` instead of `Array#length`. | ✅ | 🔧 | |
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| [prefer-spread](docs/rules/prefer-spread.md) | Prefer the spread operator over `Array.from(…)`, `Array#concat(…)`, `Array#slice()` and `String#split('')`. | ✅ | 🔧 | 💡 |
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| [prefer-spread](docs/rules/prefer-spread.md) | Prefer the spread operator over `Array.from(…)`, `Array#concat(…)`, `Array#{slice,toSpliced}()` and `String#split('')`. | ✅ | 🔧 | 💡 |
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| [prefer-string-replace-all](docs/rules/prefer-string-replace-all.md) | Prefer `String#replaceAll()` over regex searches with the global flag. | | 🔧 | |
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| [prefer-string-slice](docs/rules/prefer-string-slice.md) | Prefer `String#slice()` over `String#substr()` and `String#substring()`. | ✅ | 🔧 | |
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| [prefer-string-starts-ends-with](docs/rules/prefer-string-starts-ends-with.md) | Prefer `String#startsWith()` & `String#endsWith()` over `RegExp#test()`. | ✅ | 🔧 | 💡 |

‎rules/prefer-spread.js

+18-1
Original file line numberDiff line numberDiff line change
@@ -16,6 +16,7 @@ const isMethodNamed = require('./utils/is-method-named.js');
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const ERROR_ARRAY_FROM = 'array-from';
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const ERROR_ARRAY_CONCAT = 'array-concat';
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const ERROR_ARRAY_SLICE = 'array-slice';
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const ERROR_ARRAY_TO_SPLICED = 'array-to-spliced';
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const ERROR_STRING_SPLIT = 'string-split';
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const SUGGESTION_CONCAT_ARGUMENT_IS_SPREADABLE = 'argument-is-spreadable';
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const SUGGESTION_CONCAT_ARGUMENT_IS_NOT_SPREADABLE = 'argument-is-not-spreadable';
@@ -26,6 +27,7 @@ const messages = {
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[ERROR_ARRAY_FROM]: 'Prefer the spread operator over `Array.from(…)`.',
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[ERROR_ARRAY_CONCAT]: 'Prefer the spread operator over `Array#concat(…)`.',
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[ERROR_ARRAY_SLICE]: 'Prefer the spread operator over `Array#slice()`.',
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[ERROR_ARRAY_TO_SPLICED]: 'Prefer the spread operator over `Array#toSpliced()`.',
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[ERROR_STRING_SPLIT]: 'Prefer the spread operator over `String#split(\'\')`.',
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[SUGGESTION_CONCAT_ARGUMENT_IS_SPREADABLE]: 'First argument is an `array`.',
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[SUGGESTION_CONCAT_ARGUMENT_IS_NOT_SPREADABLE]: 'First argument is not an `array`.',
@@ -56,6 +58,14 @@ const arraySliceCallSelector = [
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'[callee.object.type!="ArrayExpression"]',
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].join('');
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const arrayToSplicedCallSelector = [
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methodCallSelector({
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method: 'toSpliced',
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argumentsLength: 0,
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}),
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'[callee.object.type!="ArrayExpression"]',
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].join('');
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const ignoredSliceCallee = [
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'arrayBuffer',
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'blob',
@@ -444,6 +454,13 @@ const create = context => {
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fix: methodCallToSpread(node, sourceCode),
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};
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},
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[arrayToSplicedCallSelector](node) {
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return {
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node: node.callee.property,
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messageId: ERROR_ARRAY_TO_SPLICED,
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fix: methodCallToSpread(node, sourceCode),
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};
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},
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[stringSplitCallSelector](node) {
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const [separator] = node.arguments;
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if (!isLiteral(separator, '')) {
@@ -495,7 +512,7 @@ module.exports = {
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meta: {
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type: 'suggestion',
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docs: {
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description: 'Prefer the spread operator over `Array.from(…)`, `Array#concat(…)`, `Array#slice()` and `String#split(\'\')`.',
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description: 'Prefer the spread operator over `Array.from(…)`, `Array#concat(…)`, `Array#{slice,toSpliced}()` and `String#split(\'\')`.',
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},
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fixable: 'code',
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hasSuggestions: true,

‎test/prefer-spread.mjs

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@@ -347,6 +347,45 @@ test.snapshot({
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],
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});
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// `Array#toSpliced`
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test.snapshot({
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valid: [
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'new Array.toSpliced()',
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'toSpliced()',
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'array[toSpliced]()',
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'array.toSpliced',
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'array.toSpliced(0)',
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'array.toSpliced(...[])',
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'array.toSpliced(...[0])',
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'array.toSpliced(0 + 0)',
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'array.toSpliced("")',
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'array.toSpliced(null)',
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'const ZERO = 0;array.toSpliced(0, ZERO)',
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'array.toSpliced(0, array.length)',
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'array.toSpliced(0, 0)',
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'array.notToSpliced()',
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// Why would someone write these
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'[...foo].toSpliced()',
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'[foo].toSpliced()',
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'array.toSpliced(100, 0)',
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'array.toSpliced(-1, 0)',
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],
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invalid: [
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'array.toSpliced()',
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'array.toSpliced().toSpliced()',
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'const copy = array.toSpliced()',
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'(( (( (( array )).toSpliced ))() ))',
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// Semicolon
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outdent`
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bar()
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foo.toSpliced()
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`,
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// `{String,TypedArray}#toSpliced` are wrongly detected
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'"".toSpliced()',
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'new Uint8Array([10, 20, 30, 40, 50]).toSpliced()',
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],
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});
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// `String#slice('')`
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test.snapshot({
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valid: [

‎test/snapshots/prefer-spread.mjs.md

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@@ -2268,6 +2268,128 @@ Generated by [AVA](https://avajs.dev).
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| ^^^^^ Prefer the spread operator over \`Array#slice()\`.␊
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`
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## Invalid #1
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1 | array.toSpliced()
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> Output
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`␊
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1 | [...array]␊
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`
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> Error 1/1
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`␊
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> 1 | array.toSpliced()␊
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| ^^^^^^^^^ Prefer the spread operator over \`Array#toSpliced()\`.␊
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`
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## Invalid #2
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1 | array.toSpliced().toSpliced()
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> Output
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`␊
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1 | [...array].toSpliced()␊
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`
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> Error 1/2
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`␊
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> 1 | array.toSpliced().toSpliced()␊
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| ^^^^^^^^^ Prefer the spread operator over \`Array#toSpliced()\`.␊
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`
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> Error 2/2
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`␊
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> 1 | array.toSpliced().toSpliced()␊
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| ^^^^^^^^^ Prefer the spread operator over \`Array#toSpliced()\`.␊
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`
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## Invalid #3
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1 | const copy = array.toSpliced()
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> Output
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`␊
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1 | const copy = [...array]␊
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`
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> Error 1/1
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`␊
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> 1 | const copy = array.toSpliced()␊
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| ^^^^^^^^^ Prefer the spread operator over \`Array#toSpliced()\`.␊
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`
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## Invalid #4
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1 | (( (( (( array )).toSpliced ))() ))
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> Output
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`␊
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1 | (( [...(( (( array )) ))] ))␊
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`
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> Error 1/1
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`␊
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> 1 | (( (( (( array )).toSpliced ))() ))␊
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| ^^^^^^^^^ Prefer the spread operator over \`Array#toSpliced()\`.␊
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`
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## Invalid #5
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1 | bar()
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2 | foo.toSpliced()
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> Output
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`␊
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1 | bar()␊
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2 | ;[...foo]␊
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`
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> Error 1/1
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`␊
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1 | bar()␊
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> 2 | foo.toSpliced()␊
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| ^^^^^^^^^ Prefer the spread operator over \`Array#toSpliced()\`.␊
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`
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## Invalid #6
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1 | "".toSpliced()
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> Output
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`␊
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1 | [...""]␊
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`
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> Error 1/1
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`␊
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> 1 | "".toSpliced()␊
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| ^^^^^^^^^ Prefer the spread operator over \`Array#toSpliced()\`.␊
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`
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## Invalid #7
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1 | new Uint8Array([10, 20, 30, 40, 50]).toSpliced()
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> Output
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`␊
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1 | [...new Uint8Array([10, 20, 30, 40, 50])]␊
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`
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> Error 1/1
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`␊
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> 1 | new Uint8Array([10, 20, 30, 40, 50]).toSpliced()␊
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| ^^^^^^^^^ Prefer the spread operator over \`Array#toSpliced()\`.␊
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`
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## Invalid #1
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1 | "string".split("")
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‎test/snapshots/prefer-spread.mjs.snap

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