text: /**
   * @fileoverview Ensures that the results of typeof are compared against a valid string
   * @author Ian Christian Myers
   */
  "use strict";
  
  //------------------------------------------------------------------------------
  // Rule Definition
  //------------------------------------------------------------------------------
  
  module.exports = {
      meta: {
          type: "problem",
  
          docs: {
              description: "enforce comparing `typeof` expressions against valid strings",
              category: "Possible Errors",
              recommended: true,
              url: "https://eslint.org/docs/rules/valid-typeof"
          },
  
          schema: [
              {
                  type: "object",
                  properties: {
                      requireStringLiterals: {
                          type: "boolean"
                      }
                  },
                  additionalProperties: false
              }
          ]
      },
  
      create(context) {
  
          const VALID_TYPES = ["symbol", "undefined", "object", "boolean", "number", "string", "function"],
              OPERATORS = ["==", "===", "!=", "!=="];
  
          const requireStringLiterals = context.options[0] && context.options[0].requireStringLiterals;
  
          /**
           * Determines whether a node is a typeof expression.
           * @param {ASTNode} node The node
           * @returns {boolean} `true` if the node is a typeof expression
           */
          function isTypeofExpression(node) {
              return node.type === "UnaryExpression" && node.operator === "typeof";
          }
  
          //--------------------------------------------------------------------------
          // Public
          //--------------------------------------------------------------------------
  
          return {
  
              UnaryExpression(node) {
                  if (isTypeofExpression(node)) {
                      const parent = context.getAncestors().pop();
  
                      if (parent.type === "BinaryExpression" && OPERATORS.indexOf(parent.operator) !== -1) {
                          const sibling = parent.left === node ? parent.right : parent.left;
  
                          if (sibling.type === "Literal" || sibling.type === "TemplateLiteral" && !sibling.expressions.length) {
                              const value = sibling.type === "Literal" ? sibling.value : sibling.quasis[0].value.cooked;
  
                              if (VALID_TYPES.indexOf(value) === -1) {
                                  context.report({ node: sibling, message: "Invalid typeof comparison value." });
                              }
                          } else if (requireStringLiterals && !isTypeofExpression(sibling)) {
                              context.report({ node: sibling, message: "Typeof comparisons should be to string literals." });
                          }
                      }
                  }
              }
  
          };
  
      }
  };
  