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eb39fafa DC |
1 | /** |
2 | * @fileoverview The rule should warn against code that tries to compare against -0. | |
3 | * @author Aladdin-ADD <hh_2013@foxmail.com> | |
4 | */ | |
5 | "use strict"; | |
6 | ||
7 | //------------------------------------------------------------------------------ | |
8 | // Rule Definition | |
9 | //------------------------------------------------------------------------------ | |
10 | ||
34eeec05 | 11 | /** @type {import('../shared/types').Rule} */ |
eb39fafa DC |
12 | module.exports = { |
13 | meta: { | |
14 | type: "problem", | |
15 | ||
16 | docs: { | |
17 | description: "disallow comparing against -0", | |
eb39fafa DC |
18 | recommended: true, |
19 | url: "https://eslint.org/docs/rules/no-compare-neg-zero" | |
20 | }, | |
21 | ||
22 | fixable: null, | |
23 | schema: [], | |
24 | ||
25 | messages: { | |
26 | unexpected: "Do not use the '{{operator}}' operator to compare against -0." | |
27 | } | |
28 | }, | |
29 | ||
30 | create(context) { | |
31 | ||
32 | //-------------------------------------------------------------------------- | |
33 | // Helpers | |
34 | //-------------------------------------------------------------------------- | |
35 | ||
36 | /** | |
37 | * Checks a given node is -0 | |
38 | * @param {ASTNode} node A node to check. | |
39 | * @returns {boolean} `true` if the node is -0. | |
40 | */ | |
41 | function isNegZero(node) { | |
42 | return node.type === "UnaryExpression" && node.operator === "-" && node.argument.type === "Literal" && node.argument.value === 0; | |
43 | } | |
44 | const OPERATORS_TO_CHECK = new Set([">", ">=", "<", "<=", "==", "===", "!=", "!=="]); | |
45 | ||
46 | return { | |
47 | BinaryExpression(node) { | |
48 | if (OPERATORS_TO_CHECK.has(node.operator)) { | |
49 | if (isNegZero(node.left) || isNegZero(node.right)) { | |
50 | context.report({ | |
51 | node, | |
52 | messageId: "unexpected", | |
53 | data: { operator: node.operator } | |
54 | }); | |
55 | } | |
56 | } | |
57 | } | |
58 | }; | |
59 | } | |
60 | }; |