ReferenceError: res is not defined in NodeJS

My NodeJS Code. I am getting correct result in console but page is not redirected to listings page

function displayCities(cname) {
    var pageData = {
      title: "Listings",
      cities: null
    };
    axios(
      //the request
      {
        url: "https://sandbox.repliers.io/listings?city=" + cname,
        method: "GET",
        headers: {
          'Content-Type': 'application/json', 
          'REPLIERS-API-KEY': 'SKoKOGhEO42QzdkZ1cowKgLGm2mwm4'
        }
      }
    ).then(function (response){
      //on success do stuff
      console.log(response.data);
      pageData.cities = response.data; //store JSON results in pageData.cities (previously null)
      res.render("listings", pageData);
    }).catch(function (error){
      console.log(error);
    });
  }