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axetroysindresorhusfisker
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Add prefer-math-min-max (#2432)
Co-authored-by: Sindre Sorhus <[email protected]> Co-authored-by: fisker <[email protected]>
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‎docs/rules/prefer-math-min-max.md

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# Prefer `Math.min()` and `Math.max()` over ternaries for simple comparisons
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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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🔧 This rule is automatically fixable by the [`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix).
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<!-- end auto-generated rule header -->
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<!-- Do not manually modify this header. Run: `npm run fix:eslint-docs` -->
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This rule enforces the use of `Math.min()` and `Math.max()` functions instead of ternary expressions when performing simple comparisons, such as selecting the minimum or maximum value between two or more options.
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By replacing ternary expressions with these functions, the code becomes more concise, easier to understand, and less prone to errors. It also enhances consistency across the codebase, ensuring that the same approach is used for similar operations, ultimately improving the overall readability and maintainability of the code.
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## Examples
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<!-- Math.min() -->
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```js
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height > 50 ? 50 : height; // ❌
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Math.min(height, 50); // ✅
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```
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```js
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height >= 50 ? 50 : height; // ❌
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Math.min(height, 50); // ✅
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```
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```js
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height < 50 ? height : 50; // ❌
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Math.min(height, 50); // ✅
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```
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```js
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height <= 50 ? height : 50; // ❌
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Math.min(height, 50); // ✅
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```
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<!-- Math.max() -->
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```js
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height > 50 ? height : 50; // ❌
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Math.max(height, 50); // ✅
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```
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```js
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height >= 50 ? height : 50; // ❌
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Math.max(height, 50); // ✅
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```
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```js
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height < 50 ? 50 : height; // ❌
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Math.max(height, 50); // ✅
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```
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```js
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height <= 50 ? 50 : height; // ❌
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Math.max(height, 50); // ✅
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```

‎readme.md

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| [prefer-json-parse-buffer](docs/rules/prefer-json-parse-buffer.md) | Prefer reading a JSON file as a buffer. | | 🔧 | |
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| [prefer-keyboard-event-key](docs/rules/prefer-keyboard-event-key.md) | Prefer `KeyboardEvent#key` over `KeyboardEvent#keyCode`. | ✅ | 🔧 | |
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| [prefer-logical-operator-over-ternary](docs/rules/prefer-logical-operator-over-ternary.md) | Prefer using a logical operator over a ternary. | ✅ | | 💡 |
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| [prefer-math-min-max](docs/rules/prefer-math-min-max.md) | Prefer `Math.min()` and `Math.max()` over ternaries for simple comparisons. | ✅ | 🔧 | |
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| [prefer-math-trunc](docs/rules/prefer-math-trunc.md) | Enforce the use of `Math.trunc` instead of bitwise operators. | ✅ | 🔧 | 💡 |
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| [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()`. | ✅ | 🔧 | |
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| [prefer-modern-math-apis](docs/rules/prefer-modern-math-apis.md) | Prefer modern `Math` APIs over legacy patterns. | ✅ | 🔧 | |

‎rules/prefer-math-min-max.js

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'use strict';
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const {fixSpaceAroundKeyword} = require('./fix/index.js');
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const MESSAGE_ID = 'prefer-math-min-max';
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const messages = {
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[MESSAGE_ID]: 'Prefer `Math.{{method}}()` to simplify ternary expressions.',
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};
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/** @param {import('eslint').Rule.RuleContext} context */
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const create = context => ({
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/** @param {import('estree').ConditionalExpression} conditionalExpression */
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ConditionalExpression(conditionalExpression) {
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const {test, consequent, alternate} = conditionalExpression;
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if (test.type !== 'BinaryExpression') {
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return;
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}
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const {operator, left, right} = test;
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const [leftText, rightText, alternateText, consequentText] = [left, right, alternate, consequent].map(node => context.sourceCode.getText(node));
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const isGreaterOrEqual = operator === '>' || operator === '>=';
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const isLessOrEqual = operator === '<' || operator === '<=';
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let method;
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// Prefer `Math.min()`
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if (
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// `height > 50 ? 50 : height`
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(isGreaterOrEqual && leftText === alternateText && rightText === consequentText)
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// `height < 50 ? height : 50`
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|| (isLessOrEqual && leftText === consequentText && rightText === alternateText)
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) {
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method = 'min';
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} else if (
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// `height > 50 ? height : 50`
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(isGreaterOrEqual && leftText === consequentText && rightText === alternateText)
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// `height < 50 ? 50 : height`
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|| (isLessOrEqual && leftText === alternateText && rightText === consequentText)
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) {
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method = 'max';
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}
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if (!method) {
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return;
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}
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return {
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node: conditionalExpression,
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messageId: MESSAGE_ID,
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data: {method},
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/** @param {import('eslint').Rule.RuleFixer} fixer */
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* fix(fixer) {
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const {sourceCode} = context;
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yield * fixSpaceAroundKeyword(fixer, conditionalExpression, sourceCode);
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const argumentsText = [left, right]
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.map(node => node.type === 'SequenceExpression' ? `(${sourceCode.getText(node)})` : sourceCode.getText(node))
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.join(', ');
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yield fixer.replaceText(conditionalExpression, `Math.${method}(${argumentsText})`);
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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,
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meta: {
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type: 'problem',
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docs: {
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description: 'Prefer `Math.min()` and `Math.max()` over ternaries for simple comparisons.',
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recommended: true,
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},
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fixable: 'code',
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messages,
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},
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};

‎test/package.mjs

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'filename-case',
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// Intended to not use `pass`/`fail` section in this rule.
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'prefer-modern-math-apis',
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'prefer-math-min-max',
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]);
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test('Every rule is defined in index file in alphabetical order', t => {

‎test/prefer-math-min-max.mjs

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import {outdent} from 'outdent';
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import {getTester} from './utils/test.mjs';
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const {test} = getTester(import.meta);
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test.snapshot({
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valid: [
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'height > 10 ? height : 20',
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'height > 50 ? Math.min(50, height) : height',
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'foo ? foo : bar',
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],
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invalid: [
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// Prefer `Math.min()`
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'height > 50 ? 50 : height',
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'height >= 50 ? 50 : height',
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'height < 50 ? height : 50',
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'height <= 50 ? height : 50',
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// Prefer `Math.min()`
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'height > maxHeight ? maxHeight : height',
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'height < maxHeight ? height : maxHeight',
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// Prefer `Math.min()`
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'window.height > 50 ? 50 : window.height',
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'window.height < 50 ? window.height : 50',
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// Prefer `Math.max()`
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'height > 50 ? height : 50',
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'height >= 50 ? height : 50',
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'height < 50 ? 50 : height',
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'height <= 50 ? 50 : height',
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// Prefer `Math.max()`
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'height > maxHeight ? height : maxHeight',
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'height < maxHeight ? maxHeight : height',
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// Edge test when there is no space between ReturnStatement and ConditionalExpression
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outdent`
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function a() {
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return +foo > 10 ? 10 : +foo
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}
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`,
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outdent`
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function a() {
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return+foo > 10 ? 10 : +foo
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}
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`,
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'(0,foo) > 10 ? 10 : (0,foo)',
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'foo.bar() > 10 ? 10 : foo.bar()',
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outdent`
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async function foo() {
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return await foo.bar() > 10 ? 10 : await foo.bar()
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}
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`,
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outdent`
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async function foo() {
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await(+foo > 10 ? 10 : +foo)
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}
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`,
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outdent`
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function foo() {
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return(foo.bar() > 10) ? 10 : foo.bar()
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}
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`,
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outdent`
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function* foo() {
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yield+foo > 10 ? 10 : +foo
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}
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`,
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'export default+foo > 10 ? 10 : +foo',
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'foo.length > bar.length ? bar.length : foo.length',
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],
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});

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