Poll the Server with Ajax and Dojo

Question

I'm using dojo.xhrPost to sent Ajax Requests
The call is wrapped by a function sendRequest()

I've now to continuously (every 3sec) send the same ajax Post to the server
How can I implement a Server Poll with Dojo? I basically need to call sendRequest() every 3 secs

Answer 1

I don't believe that Dojo has a method built-in for polling, so here's a generic method that's applicable across frameworks

var Poll = function(pollFunction, intervalTime) {
    var intervalId = null;

    this.start = function(newPollFunction, newIntervalTime) {
        pollFunction = newPollFunction || pollFunction;
        intervalTime = newIntervalTime || intervalTime;

        if ( intervalId ) {
            this.stop();
        }

        intervalId = setInterval(pollFunction, intervalTime);
    };

    this.stop = function() {
        clearInterval(intervalId);
    };
};

Usage:

var p = new Poll(function() { console.log("hi!"); }, 1000);
p.start();
setTimeout(function() { p.stop();}, 5000);

Or in your case:

var p = new Poll(sendRequest, 3000);
p.start();

If you want this as a Dojo package, then the following is a trivial extension:

dojo.provide("Poll");

dojo.declare("Poll", null, {
    intervalId:   null,
    pollFunction: null,
    intervalTime: null,

    constructor: function(newPollFunction, newIntervalTime) {
        this.pollFunction = newPollFunction;
        this.intervalTime = newIntervalTime;
    },

    start: function(newPollFunction, newIntervalTime) {
        this.pollFunction = newPollFunction || this.pollFunction;
        this.intervalTime = newIntervalTime || this.intervalTime;

        this.stop();
        this.intervalId = setInterval(this.pollFunction, this.intervalTime);
    },

    stop: function() {
        clearInterval(this.intervalId);
    }
});

Usage:

var p = new Poll(function() {console.log("hi");}, 250);
p.start();
setTimeout(dojo.hitch(p, p.stop), 1000);