Polling every 10 seonds

问题

In the code below, I had the expectation that this would create a polling loop that would fire off every 10 seconds to get a "job status report" from the server. It seems it is creating over 100 calls per second.

I got my education from this excellent article, but I seem to be misreading it.

function UpdateEstimates() {
var request = { jobID: ExportVM.get("ticketID") };
var jqxhr = $.ajax({
    type: "GET",
    url: AppGlobals.serverURL + "GetJobStatus",
    data: request,
    contentType: "application/json; charset=utf-8",
    complete: UpdateEstimates,
    timeout: 10000,
    dataType: "json"
});
jqxhr.done(function (data) { NewEstimates(data); });
jqxhr.fail(function (data) { alert('new estimates request failed'); });

}

The call is very low overhead, so I can handle easily 1 second updates, but I really don't like the continuous 100/sec rate very much. Is there some way to introduce a delay into the call loop?

回答1:

timeout in $.ajax is not doing what you actually think. It just sets the timeout for that particular call (maximum allowed time). You will have to wrap this in setTimeout function.

回答2:

I would suggest to re-trigger the timeout on the 'complete' hook. In this fashion you prevent overlapping reqs.

Tear the 'timeout' param off - as @tomca32 explained timeout is about a req that would take too long.

It would be something like:

function UpdateEstimates() {
var request = { jobID: ExportVM.get("ticketID") };
var jqxhr = $.ajax({
    type: "GET",
    url: AppGlobals.serverURL + "GetJobStatus",
    data: request,
    complete: scheduleUpdEstimates,
    contentType: "application/json; charset=utf-8",
    dataType: "json"
});
jqxhr.done(function (data) { NewEstimates(data); });
jqxhr.fail(function (data) { alert('new estimates request failed'); });


function scheduleUpdEstimates(){
    setTimeout(function(){ UpdateEstimates(); }, 10000);
}

来源：https://stackoverflow.com/questions/16364928/polling-every-10-seonds

标签

jquery

polling