Monitoring time while using your skill

I wanted to explore making a game using the Alexa.  I thought it would be useful to know how long the game had been running.  Here is an example of how I am able to track the time elapsed since launching a skill.

Intent Schema

{

  "intents": [

     {

      "intent": "TimeIntent"

     },

    {

      "intent": "AMAZON.StopIntent"

    }

    ]

}

Sample Utterances

TimeIntent How much time has passed

I only have one intent that I use to ask for the elapsed time.  And the StopIntent just helps me quit the skill.  All of the work happens in the Lambda function.

var tickingClockMP3 = 

    "https://alexafiles.blob.core.windows.net/demo/ticking-clock.mp3";

exports.handler = function (event, context) {

    var attributes = {};

    

    if (event.session.new) {

        attributes = { startTime: event.request.timestamp };

    }

    else {

        attributes = 

        { 

            startTime: event.session.attributes.startTime,

            timeDiff: (new Date(event.request.timestamp) - 

                       new Date(event.session.attributes.startTime)) / 1000

        };

    }

    

    try {

        if (event.request.type === "SessionEndedRequest") {

                    onSessionEnded(event.request, event.session);

                    context.succeed();

        }

        else if(event.request.type === "LaunchRequest")

            context.succeed(buildTickerResponse(attributes, false));

        else if(event.request.type === "IntentRequest") {

            var output = "" + (attributes.timeDiff || 0) 

                       + " seconds have past.

";

            context.succeed(buildTickerResponse(attributes, false, output));

        }

        else

            context.succeed(buildTickerResponse(attributes, false));

    } catch (e) {

        context.fail("Exception: " + e);

    }

};

function buildTickerResponse(attributes, shouldEndSession, output) {

    return {

        version: "1.0",

        sessionAttributes: attributes,

        response: {

            outputSpeech: {

                type: "SSML",

                ssml: output || ""

            },

            reprompt: {

                outputSpeech: {

                    type: "SSML",

                    ssml: "At anytime you can say... " + 

                          "Alexa, how much time has past?

"

                }

            },

            shouldEndSession: false

        }

    };

}

A few things to note here.  

1. When creating MP3s, make sure you follow the rules about where they can be hosted and the allowed format.  I used FFMPEG to fix it up: ffmpeg -i input.mp3 -b:a 48k -ar 16000 output.mp3.
2. While the SSML is playing the audio, the only way to get Alexa to hear you again, you have to say her name.
3. I store the startTime as an attribute.  I have to copy that value over to the new attributes object I send back each time.

That's it!  You can now keep track of how much time has past since your skill started.