jQuery AJAX loop to refresh jQueryUI ProgressBar

Question

I\'ve got a jQueryUI progressbar that should show the percentage of a query done. Oracle has a nice system table that lets you see operations that will take more than 10 se

Answer 1

I believe what you want to do is call the getProgress function again when it completes.

You would do this by adding the 'complete' param to the ajax call

$.ajax({
  //this is where your stuff already is
  ,complete: getProgress()

  //we add a timeout so it doesn't run everytime it completes, only when we want to update the progress bar.
  ,timeout: 10000 //this is 10 seconds
});

This is a method commonly referred to as 'polling'.

Answer 2

Instead of setTimeout(GetProgress(), 3000), you would want:

function StartLoop(){
    for (var i = 0; i < 100; i++) {
        setTimeout(GetProgress(), 3000*i);
    }
}

Otherwise, all 100 will fire off after 3 seconds. Instead, you want 0, 3000, 6000, 9000, etc., i.e. 3000*i;

Better, you could use setInterval and clearInterval:

var myInterval = setInterval(GetProgress(), 3000);

and in the callback, do:

$.ajax({
    url: "query.aspx/GetProgress",
    success: function (msg) {
        var data = $.parseJSON(msg.d);
        $("#pbrQuery").progressbar("value", data.value);

        if (data.value == 100) {
            isDone = true;
            clearInterval(myInterval);
        }          
    }
});

clearInterval will stop it from calling GetProgress() again. Using the setInterval method means you don't have to know how many poll loops you need up front. It will simply continue until you are done.

Or better yet, you can call GetProgress() from the ajax callback, with the advantage that it will only poll again once you have a response from your query:

function GetProgress() {
    $.ajax({
        url: "query.aspx/GetProgress",
        success: function (msg) {
            var data = $.parseJSON(msg.d);
            $("#pbrQuery").progressbar("value", data.value);

            if (data.value == 100) {
                isDone = true;
            } else {
                setTimeout(GetProgress(), 2000);
            }
        }
    });
}

Then just call GetProgress() once to initiate the loop.