/**
   * @fileoverview Rule to flag comparisons to the value NaN
   * @author James Allardice
   */
  
  "use strict";
  
  //------------------------------------------------------------------------------
  // Rule Definition
  //------------------------------------------------------------------------------
  
  module.exports = {
      meta: {
          docs: {
              description: "require calls to `isNaN()` when checking for `NaN`",
              category: "Possible Errors",
              recommended: true
          },
  
          schema: []
      },
  
      create(context) {
  
          return {
              BinaryExpression(node) {
                  if (/^(?:[<>]|[!=]=)=?$/.test(node.operator) && (node.left.name === "NaN" || node.right.name === "NaN")) {
                      context.report({ node, message: "Use the isNaN function to compare with NaN." });
                  }
              }
          };
  
      }
  };