/** * @fileoverview A rule to disallow negated left operands of the `in` operator * @author Michael Ficarra * @deprecated in ESLint v3.3.0 */ "use strict"; //------------------------------------------------------------------------------ // Rule Definition //------------------------------------------------------------------------------ module.exports = { meta: { docs: { description: "disallow negating the left operand in `in` expressions", category: "Possible Errors", recommended: false, replacedBy: ["no-unsafe-negation"], url: "https://eslint.org/docs/rules/no-negated-in-lhs" }, deprecated: true, schema: [] }, create(context) { return { BinaryExpression(node) { if (node.operator === "in" && node.left.type === "UnaryExpression" && node.left.operator === "!") { context.report({ node, message: "The 'in' expression's left operand is negated." }); } } }; } };