| /** | |
| * @fileoverview The rule should warn against code that tries to compare against -0. | |
| * @author Aladdin-ADD <hh_2013@foxmail.com> | |
| */ | |
| "use strict"; | |
| //------------------------------------------------------------------------------ | |
| // Rule Definition | |
| //------------------------------------------------------------------------------ | |
| module.exports = { | |
| meta: { | |
| type: "problem", | |
| docs: { | |
| description: "disallow comparing against -0", | |
| category: "Possible Errors", | |
| recommended: true, | |
| url: "https://eslint.org/docs/rules/no-compare-neg-zero" | |
| }, | |
| fixable: null, | |
| schema: [], | |
| messages: { | |
| unexpected: "Do not use the '{{operator}}' operator to compare against -0." | |
| } | |
| }, | |
| create(context) { | |
| //-------------------------------------------------------------------------- | |
| // Helpers | |
| //-------------------------------------------------------------------------- | |
| /** | |
| * Checks a given node is -0 | |
| * | |
| * @param {ASTNode} node - A node to check. | |
| * @returns {boolean} `true` if the node is -0. | |
| */ | |
| function isNegZero(node) { | |
| return node.type === "UnaryExpression" && node.operator === "-" && node.argument.type === "Literal" && node.argument.value === 0; | |
| } | |
| const OPERATORS_TO_CHECK = new Set([">", ">=", "<", "<=", "==", "===", "!=", "!=="]); | |
| return { | |
| BinaryExpression(node) { | |
| if (OPERATORS_TO_CHECK.has(node.operator)) { | |
| if (isNegZero(node.left) || isNegZero(node.right)) { | |
| context.report({ | |
| node, | |
| messageId: "unexpected", | |
| data: { operator: node.operator } | |
| }); | |
| } | |
| } | |
| } | |
| }; | |
| } | |
| }; |