A quick example with PubNub, and using the Ping API to detect the latency and connectivity of the device. This type of test provides insight into deliverability performance expectations which can be directly relayed to the user allowing you (the app developer) to set the expectations of the experience based on the user's current connection speed.

Check out this code. It shows you how to get started with detecting device latency. It simply sends a ping to PubNub and tracks round-trip send/receive status. Note that a slow response is typically related to the connection speed of the device and also relates to network traffic capabilities in the local area.

function connection_latency(callback) {
    connection_latency.start = now();

    PUBNUB.time(function(){
        callback(now() - connection_latency.start);
        setTimeout( function(){ connection_latency(callback) }, 1000 );
        clearInterval(connection_latency.ival);
        connection_latency.ival = 0;
    });

    if (connection_latency.ival) return;

    connection_latency.ival = setInterval( function() {
        callback(now() - connection_latency.start);
    }, 1500 );

    return connection_latency.ival;
}
function now(){return+new Date}

This code shows delivery round-trip speed testing using PubNub's high available Global Distribution Network.

Simple use this method by following the example:

connection_latency(function(latency){
    // Show currnet Latency
    console.log(latency);
});

This code is executed periodically for a continuous latency test.

That's it! See the full example in the latency.html file in this directory.