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prefer-array-some: Check Array#{findIndex,findLastIndex}() (#2370)
Co-authored-by: Sindre Sorhus <[email protected]>
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‎docs/rules/prefer-array-some.md‎

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@@ -1,4 +1,4 @@
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# Prefer `.some(…)` over `.filter(…).length` check and `.{find,findLast}(…)`
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# Prefer `.some(…)` over `.filter(…).length` check and `.{find,findLast,findIndex,findLastIndex}(…)`
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💼 This rule is enabled in the ✅ `recommended` [config](https://github.com/sindresorhus/eslint-plugin-unicorn#preset-configs-eslintconfigjs).
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@@ -17,7 +17,11 @@ We only check `.filter().length > 0` and `.filter().length !== 0`. These two non
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- Comparing the result of [`Array#find()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find) or [`Array#findLast()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findLast) with `undefined`.
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This rule is fixable for `.filter(…).length` check and has a suggestion for `.{find,findLast}(…)`.
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- Using [`Array#findIndex()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex) or [`Array#findLastIndex()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findLastIndex) to ensure at least one element in the array passes a given check.
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This rule is fixable for `.filter(…).length` checks and `.{findIndex,findLastIndex}(…)`.
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This rule provides a suggestion for `.{find,findLast}(…)`.
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## Fail
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@@ -44,11 +48,11 @@ const foo = array.find(element => isUnicorn(element)) ? bar : baz;
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```
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```js
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const hasUnicorn = array.find(element => isUnicorn(element) !== undefined;
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const hasUnicorn = array.find(element => isUnicorn(element)) !== undefined;
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```
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```js
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const hasUnicorn = array.find(element => isUnicorn(element) != null;
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const hasUnicorn = array.find(element => isUnicorn(element)) != null;
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```
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```js
@@ -62,11 +66,19 @@ const foo = array.findLast(element => isUnicorn(element)) ? bar : baz;
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```
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```js
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const hasUnicorn = array.findLast(element => isUnicorn(element) !== undefined;
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const hasUnicorn = array.findLast(element => isUnicorn(element)) !== undefined;
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```
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```js
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const hasUnicorn = array.findLast(element => isUnicorn(element)) != null;
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```
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```js
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const hasUnicorn = array.findIndex(element => isUnicorn(element)) !== -1;
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```
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```js
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const hasUnicorn = array.findLast(element => isUnicorn(element) != null;
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const hasUnicorn = array.findLastIndex(element => isUnicorn(element)) !== -1;
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```
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```vue

‎readme.md‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -176,7 +176,7 @@ If you don't use the preset, ensure you use the same `env` and `parserOptions` c
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| [prefer-array-flat](docs/rules/prefer-array-flat.md) | Prefer `Array#flat()` over legacy techniques to flatten arrays. | ✅ | 🔧 | |
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| [prefer-array-flat-map](docs/rules/prefer-array-flat-map.md) | Prefer `.flatMap(…)` over `.map(…).flat()`. | ✅ | 🔧 | |
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| [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. | ✅ | 🔧 | 💡 |
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| [prefer-array-some](docs/rules/prefer-array-some.md) | Prefer `.some(…)` over `.filter(…).length` check and `.{find,findLast}(…)`. | ✅ | 🔧 | 💡 |
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| [prefer-array-some](docs/rules/prefer-array-some.md) | Prefer `.some(…)` over `.filter(…).length` check and `.{find,findLast,findIndex,findLastIndex}(…)`. | ✅ | 🔧 | 💡 |
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| [prefer-at](docs/rules/prefer-at.md) | Prefer `.at()` method for index access and `String#charAt()`. | ✅ | 🔧 | 💡 |
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| [prefer-blob-reading-methods](docs/rules/prefer-blob-reading-methods.md) | Prefer `Blob#arrayBuffer()` over `FileReader#readAsArrayBuffer(…)` and `Blob#text()` over `FileReader#readAsText(…)`. | ✅ | | |
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| [prefer-code-point](docs/rules/prefer-code-point.md) | Prefer `String#codePointAt(…)` over `String#charCodeAt(…)` and `String.fromCodePoint(…)` over `String.fromCharCode(…)`. | ✅ | | 💡 |

‎rules/prefer-array-some.js‎

Lines changed: 64 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -40,10 +40,14 @@ const isCheckingUndefined = node =>
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&& isLiteral(node.parent.right, null)
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)
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);
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const isNegativeOne = node => node.type === 'UnaryExpression' && node.operator === '-' && node.argument && node.argument.type === 'Literal' && node.argument.value === 1;
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const isLiteralZero = node => isLiteral(node, 0);
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/** @param {import('eslint').Rule.RuleContext} context */
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const create = context => ({
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CallExpression(callExpression) {
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const create = context => {
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// `.find(…)`
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// `.findLast(…)`
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context.on('CallExpression', callExpression => {
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if (!isMethodCall(callExpression, {
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methods: ['find', 'findLast'],
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minimumArguments: 1,
@@ -86,8 +90,61 @@ const create = context => ({
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},
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],
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};
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},
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BinaryExpression(binaryExpression) {
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});
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// These operators also used in `prefer-includes`, try to reuse the code in future
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// `.{findIndex,findLastIndex}(…) !== -1`
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// `.{findIndex,findLastIndex}(…) != -1`
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// `.{findIndex,findLastIndex}(…) > -1`
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// `.{findIndex,findLastIndex}(…) === -1`
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// `.{findIndex,findLastIndex}(…) == -1`
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// `.{findIndex,findLastIndex}(…) >= 0`
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// `.{findIndex,findLastIndex}(…) < 0`
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context.on('BinaryExpression', binaryExpression => {
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const {left, right, operator} = binaryExpression;
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if (!(
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isMethodCall(left, {
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methods: ['findIndex', 'findLastIndex'],
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argumentsLength: 1,
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optionalCall: false,
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optionalMember: false,
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})
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&& (
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(['!==', '!=', '>', '===', '=='].includes(operator) && isNegativeOne(right))
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|| (['>=', '<'].includes(operator) && isLiteralZero(right))
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)
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)) {
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return;
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}
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const methodNode = left.callee.property;
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return {
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node: methodNode,
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messageId: ERROR_ID_ARRAY_SOME,
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data: {method: methodNode.name},
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* fix(fixer) {
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if (['===', '==', '<'].includes(operator)) {
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yield fixer.insertTextBefore(binaryExpression, '!');
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}
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yield fixer.replaceText(methodNode, 'some');
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const operatorToken = context.sourceCode.getTokenAfter(
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left,
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token => token.type === 'Punctuator' && token.value === operator,
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);
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const [start] = operatorToken.range;
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const [, end] = binaryExpression.range;
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yield fixer.removeRange([start, end]);
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},
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};
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});
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// `.filter(…).length > 0`
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// `.filter(…).length !== 0`
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context.on('BinaryExpression', binaryExpression => {
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if (!(
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// We assume the user already follows `unicorn/explicit-length-check`. These are allowed in that rule.
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(binaryExpression.operator === '>' || binaryExpression.operator === '!==')
@@ -139,16 +196,16 @@ const create = context => ({
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// The `BinaryExpression` always ends with a number or `)`, no need check for ASI
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},
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};
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},
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});
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});
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};
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/** @type {import('eslint').Rule.RuleModule} */
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module.exports = {
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create: checkVueTemplate(create),
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meta: {
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type: 'suggestion',
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docs: {
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description: 'Prefer `.some(…)` over `.filter(…).length` check and `.{find,findLast}(…)`.',
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description: 'Prefer `.some(…)` over `.filter(…).length` check and `.{find,findLast,findIndex,findLastIndex}(…)`.',
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recommended: true,
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},
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fixable: 'code',

‎test/prefer-array-some.mjs‎

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Original file line numberDiff line numberDiff line change
@@ -210,6 +210,40 @@ test.snapshot({
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],
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});
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// `.{findIndex,findLastIndex}(…) !== -1`
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// `.{findIndex,findLastIndex}(…) != -1`
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// `.{findIndex,findLastIndex}(…) > -1`
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// `.{findIndex,findLastIndex}(…) === -1`
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// `.{findIndex,findLastIndex}(…) == -1`
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// `.{findIndex,findLastIndex}(…) >= 0`
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// `.{findIndex,findLastIndex}(…) < 0`
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test.snapshot({
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valid: [
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'foo.notMatchedMethod(bar) !== -1',
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'new foo.findIndex(bar) !== -1',
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'foo.findIndex(bar, extraArgument) !== -1',
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'foo.findIndex(bar) instanceof -1',
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'foo.findIndex(...bar) !== -1',
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// We are not ignoring ``{_,lodash,underscore}.{findIndex,findLastIndex}`
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// but it doesn't make sense to use them with one argument
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'_.findIndex(bar)',
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'_.findIndex(foo, bar)',
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],
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invalid: [
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...[
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'foo.findIndex(bar) !== -1',
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'foo.findIndex(bar) != -1',
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'foo.findIndex(bar) > - 1',
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'foo.findIndex(bar) === -1',
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'foo.findIndex(bar) == - 1',
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'foo.findIndex(bar) >= 0',
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'foo.findIndex(bar) < 0',
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].flatMap(code => [code, code.replace('findIndex', 'findLastIndex')]),
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'foo.findIndex(bar) !== (( - 1 ))',
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'foo.findIndex(element => element.bar === 1) !== (( - 1 ))',
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],
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});
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test.vue({
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valid: [],
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invalid: [

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