/** * @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 //------------------------------------------------------------------------------ /** @type {import('../types').Rule.RuleModule} */ module.exports = { meta: { type: "problem", docs: { description: "Disallow negating the left operand in `in` expressions", recommended: false, url: "https://eslint.org/docs/latest/rules/no-negated-in-lhs", }, deprecated: { message: "Renamed rule.", url: "https://eslint.org/blog/2016/08/eslint-v3.3.0-released/#deprecated-rules", deprecatedSince: "3.3.0", availableUntil: null, replacedBy: [ { rule: { name: "no-unsafe-negation", url: "https://eslint.org/docs/rules/no-unsafe-negation", }, }, ], }, schema: [], messages: { negatedLHS: "The 'in' expression's left operand is negated.", }, }, create(context) { return { BinaryExpression(node) { if ( node.operator === "in" && node.left.type === "UnaryExpression" && node.left.operator === "!" ) { context.report({ node, messageId: "negatedLHS" }); } }, }; }, };