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 11module.exports = { 12 meta: { 13 type: "problem", 14 15 docs: { 16 description: "disallow comparing against -0", 17 category: "Possible Errors", 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}; 61