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