JQuery in AJAX

Question

Hi..........
 
How can we use JQuery in AJAX and define technique for JQuery?

$(document).ready(function() {

        $("#getWeatherReport").click(function(){

            $cityName = document.getElementById("cityName").value;

            $.post("WeatherServlet", {cityName:$cityName}, function(data) {

                alert(data);

                $("#weatherReport").html(data);

            });