eslint/lib/rules/no-negated-in-lhs.js

   1 /**
   2  * @fileoverview A rule to disallow negated left operands of the `in` operator
   3  * @author Michael Ficarra
   4  * @deprecated in ESLint v3.3.0
   5  */
   6
   7 "use strict";
   8
   9 //------------------------------------------------------------------------------
  10 // Rule Definition
  11 //------------------------------------------------------------------------------
  12
  13 /** @type {import('../shared/types').Rule} */
  14 module.exports = {
  15     meta: {
  16         type: "problem",
  17
  18         docs: {
  19             description: "disallow negating the left operand in `in` expressions",
  20             recommended: false,
  21             url: "https://eslint.org/docs/rules/no-negated-in-lhs"
  22         },
  23
  24         replacedBy: ["no-unsafe-negation"],
  25
  26         deprecated: true,
  27         schema: [],
  28
  29         messages: {
  30             negatedLHS: "The 'in' expression's left operand is negated."
  31         }
  32     },
  33
  34     create(context) {
  35
  36         return {
  37
  38             BinaryExpression(node) {
  39                 if (node.operator === "in" && node.left.type === "UnaryExpression" && node.left.operator === "!") {
  40                     context.report({ node, messageId: "negatedLHS" });
  41                 }
  42             }
  43         };
  44
  45     }
  46 };