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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,64 @@ | ||
| # Disallow `if` statements as the only statement in `if` blocks without `else` | ||
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| This rule adds onto the built-in [`no-lonely-if`](https://eslint.org/docs/rules/no-lonely-if) rule, which only forbids `if` statements in `else`, not in `if`. | ||
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| This rule is fixable. | ||
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| ## Fail | ||
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| ```js | ||
| if (foo) { | ||
| if (bar) { | ||
| // … | ||
| } | ||
| } | ||
| ``` | ||
|
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| ```js | ||
| if (foo) { | ||
| // … | ||
| } else if (bar) { | ||
| if (baz) { | ||
| // … | ||
| } | ||
| } | ||
| ``` | ||
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| ## Pass | ||
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| ```js | ||
| if (foo && bar) { | ||
| // … | ||
| } | ||
| ``` | ||
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| ```js | ||
| if (foo) { | ||
| // … | ||
| } else if (bar && baz) { | ||
| // … | ||
| } | ||
| ``` | ||
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| ```js | ||
| if (foo) { | ||
| // … | ||
| } else if (bar) { | ||
| if (baz) { | ||
| // … | ||
| } | ||
| } else { | ||
| // … | ||
| } | ||
| ``` | ||
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| ```js | ||
| // Built-in rule `no-lonely-if` case https://eslint.org/docs/rules/no-lonely-if | ||
| if (foo) { | ||
| // … | ||
| } else { | ||
| if (bar) { | ||
| // … | ||
| } | ||
| } | ||
| ``` |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,90 @@ | ||
| 'use strict'; | ||
| const getDocumentationUrl = require('./utils/get-documentation-url'); | ||
| const needsSemicolon = require('./utils/needs-semicolon'); | ||
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| const MESSAGE_ID = 'no-lonely-if'; | ||
| const messages = { | ||
| [MESSAGE_ID]: 'Unexpected `if` as the only statement in a `if` block without `else`.' | ||
| }; | ||
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| const ifStatementWithoutAlternate = 'IfStatement:not([alternate])'; | ||
| const selector = `:matches(${ | ||
| [ | ||
| // `if (a) { if (b) {} }` | ||
| [ | ||
| ifStatementWithoutAlternate, | ||
| '>', | ||
| 'BlockStatement.consequent', | ||
| '[body.length=1]', | ||
| '>', | ||
| `${ifStatementWithoutAlternate}.body` | ||
| ].join(''), | ||
| // `if (a) if (b) {}` | ||
| `${ifStatementWithoutAlternate} > ${ifStatementWithoutAlternate}.consequent` | ||
| ].join(', ') | ||
| })`; | ||
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| // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence#Table | ||
| // Lower precedence than `&&` | ||
| const needParenthesis = node => ( | ||
| (node.type === 'LogicalExpression' && (node.operator === '||' || node.operator === '??')) || | ||
| node.type === 'ConditionalExpression' || | ||
| node.type === 'AssignmentExpression' || | ||
| node.type === 'YieldExpression' || | ||
| node.type === 'SequenceExpression' | ||
| ); | ||
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| const create = context => { | ||
| const sourceCode = context.getSourceCode(); | ||
| const getText = node => sourceCode.getText(node); | ||
| const getTestNodeText = node => needParenthesis(node) ? `(${getText(node)})` : getText(node); | ||
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| return { | ||
| [selector](inner) { | ||
| const {parent} = inner; | ||
| const outer = parent.type === 'BlockStatement' ? parent.parent : parent; | ||
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| context.report({ | ||
| node: inner, | ||
| messageId: MESSAGE_ID, | ||
| * fix(fixer) { | ||
| // Merge `test` | ||
| yield fixer.replaceText(outer.test, `${getTestNodeText(outer.test)} && ${getTestNodeText(inner.test)}`); | ||
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| // Replace `consequent` | ||
| const {consequent} = inner; | ||
| let consequentText = getText(consequent); | ||
| // If the `if` statement has no block, and is not followed by a semicolon, | ||
| // make sure that fixing the issue would not change semantics due to ASI. | ||
| // Similar logic https://github.com/eslint/eslint/blob/2124e1b5dad30a905dc26bde9da472bf622d3f50/lib/rules/no-lonely-if.js#L61-L77 | ||
| if ( | ||
| consequent.type !== 'BlockStatement' && | ||
| outer.consequent.type === 'BlockStatement' && | ||
| !consequentText.endsWith(';') | ||
| ) { | ||
| const lastToken = sourceCode.getLastToken(consequent); | ||
| const nextToken = sourceCode.getTokenAfter(outer); | ||
| if (needsSemicolon(lastToken, sourceCode, nextToken.value)) { | ||
| consequentText += ';'; | ||
| } | ||
| } | ||
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| yield fixer.replaceText(outer.consequent, consequentText); | ||
| } | ||
| }); | ||
| } | ||
| }; | ||
| }; | ||
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| module.exports = { | ||
| create, | ||
| meta: { | ||
| type: 'suggestion', | ||
| docs: { | ||
| url: getDocumentationUrl(__filename) | ||
| }, | ||
| fixable: 'code', | ||
| messages | ||
| } | ||
| }; |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,126 @@ | ||
| import {outdent} from 'outdent'; | ||
| import {test} from './utils/test'; | ||
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| test({ | ||
| valid: [ | ||
| outdent` | ||
| if (a) { | ||
| if (b) { | ||
| } | ||
| } else {} | ||
| `, | ||
| outdent` | ||
| if (a) { | ||
| if (b) { | ||
| } | ||
| foo(); | ||
| } else {} | ||
| `, | ||
| outdent` | ||
| if (a) { | ||
| } else { | ||
| if (y) {} | ||
| } | ||
| `, | ||
| outdent` | ||
| if (a) { | ||
| b ? c() : d() | ||
| } | ||
| ` | ||
| ], | ||
| invalid: [] | ||
| }); | ||
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| test.visualize([ | ||
| outdent` | ||
| if (a) { | ||
| if (b) { | ||
| } | ||
| } | ||
| `, | ||
| // Inner one is `BlockStatement` | ||
| outdent` | ||
| if (a) if (b) { | ||
| foo(); | ||
| } | ||
| `, | ||
| // Outer one is `BlockStatement` | ||
| outdent` | ||
| if (a) { | ||
| if (b) foo(); | ||
| } | ||
| `, | ||
| // No `BlockStatement` | ||
| 'if (a) if (b) foo();', | ||
| // `EmptyStatement` | ||
| 'if (a) if (b);', | ||
| // Nested | ||
| outdent` | ||
| if (a) { | ||
| if (b) { | ||
| // Should not report | ||
| } | ||
| } else if (c) { | ||
| if (d) { | ||
| } | ||
| } | ||
| `, | ||
| // Need parenthesis | ||
| outdent` | ||
| function * foo() { | ||
| if (a || b) | ||
| if (a ?? b) | ||
| if (a ? b : c) | ||
| if (a = b) | ||
| if (a += b) | ||
| if (a -= b) | ||
| if (a &&= b) | ||
| if (yield a) | ||
| if (a, b); | ||
| } | ||
| `, | ||
| // Should not add parenthesis | ||
| outdent` | ||
| async function foo() { | ||
| if (a) | ||
| if (await a) | ||
| if (a.b) | ||
| if (a && b); | ||
| } | ||
| `, | ||
| // Don't case parenthesis in outer test | ||
| 'if (((a || b))) if (((c || d)));', | ||
| // Comments | ||
| outdent` | ||
| if /* will keep */ | ||
| ( | ||
| /* will keep */ | ||
| a /* will keep */ | ||
| .b /* will keep */ | ||
| ) /* keep */{ | ||
| /* will remove */ | ||
| if ( | ||
| /* will remove */ | ||
| c /* will keep */ | ||
| .d /* will remove */ | ||
| ) { | ||
| /* will keep */ | ||
| foo(); | ||
| /* will keep */ | ||
| } | ||
| /* will remove */ | ||
| } | ||
| `, | ||
| // Semicolon | ||
| outdent` | ||
| if (a) { | ||
| if (b) foo() | ||
| } | ||
| [].forEach(bar) | ||
| `, | ||
| outdent` | ||
| if (a) | ||
| if (b) foo() | ||
| ;[].forEach(bar) | ||
| ` | ||
| ]); |
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