how to schedule ajax calls every N seconds?

Question

If I want a whole page to reload every N seconds, I would put something like this in the HTML: meta http-equiv=\"refresh\" content=\"5\"

Is there a sta

Answer 1

I assume that there is a servlet with URL Pattern /UpdateCount is configured in web.xml to provide dynamic data/content and there is a div element countStatDiv in the jsp page.

The following code refreshes/updates the content of countStatDiv at every 30 seconds using GET method and variable seconds value can be changed according to the need:

                <script>
                    var request;
                    var seconds=30;
                    function getRequestObject(){
                    setInterval(function() {sendRequest();},seconds*1000);
                    if (window.ActiveXObject){
                    return (new ActiveXObject("Microsoft.XMLHTTP"));
                    } else if (window.XMLHttpRequest){
                    return(new XMLHttpRequest());
                    } else {
                    return (null);
                    }
                    }
                    function sendRequest(){
                    request = getRequestObject();
                    request.onreadystatechange = handleResponse;
                    request.open("GET", "../UpdateCount", true);
                    request.send(null);
                    }
                    function handleResponse(){
                    if((request.readyState == 4)&amp;&amp;(request.status == 200)){
                    var serverResponse = request.responseText;
                    var statCtrl=document.getElementById("countStatDiv");
                    statCtrl.innerHTML=serverResponse;
                    }
                    }
                </script>

Answer 2

You could use setTimeout or setInterval (the latter is probably best suited to what you want to do).

setInterval(makeRequest, (10 * 1000));

...where makeRequest is a function that reloads some content via AJAX.

Answer 3

function proxy()
{
  /* implement call to your Ajax method */
}

setInterval( proxy, 1000 ); // last arg is in milliseconds

Answer 4

You can use serInterval method of javascript:
Just write down the lines at the bottom of your page:

<script>
window.setInterval(function(){
  ajaxCallFunction();  //calling every 5 seconds
}, 5000);

function ajaxCallFunction(){
    //this function uses ajax to interact with the server
}
<script>