weather.fetchWeather("Yelagiri");

Instead of typing this Yelagiri manually, I want the output (area) of the following snippet to be the input of the function.

function processRequest(e) {
        if (xhr.readyState == 4 && xhr.status == 200) {
            var response = JSON.parse(xhr.responseText);
            var city = response.address.city;
            console.log(city);
            var area = city;
            return;

thanks.