| /** |
| * @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 } |
| }); |
| } |
| } |
| } |
| }; |
| } |
| }; |