client.addEventSync()

[will123195]

Is it possible to call addEvent synchronously?

For example:

window.onbeforeunload = function() {
  client.addEventSync('my-collection');
}

[will123195]

This is a workaround:

window.onbeforeunload = function() {
  var request = new XMLHttpRequest();
  var url = 'https://api.keen.io/3.0/projects/' + projectId + '/events/' + collection + '?api_key=' + writeKey + '&data=' + encodeURIComponent( Keen.Base64.encode( JSON.stringify(data) ) );
  request.open('GET', url, false);  // synchronous
  request.send(null);
}

[dustinlarimer]

@will123195 help me understand that – would that let you fire a payload off before the window closes?

[will123195]

Yes, for example I'm tracking how long the user was on the page.

[dustinlarimer]

hey @will123195 sorry for the lag! I really like this idea, we're discussing the best way to expose this functionality.. can you think of any other scenarios where you would want a synchronous request?

[will123195]

It would help if you need your events to be logged in a specific order. Surely there are more performant ways to achieve that without blocking i/o, but could be convenient for testing or debugging things easily.

[dustinlarimer]

@will123195 haven't forgotten about this.. not sure how we'll expose in the library, but here's a cool workaround I found that has a high success rate on mobile (onpagehide):

function setUnloadListener(){
    var attachEvent, whichEvent;
    if (window.onpagehide || window.onpagehide === null) {
      window.addEventListener("pagehide", handleExit, false);
    }
    else {
      attachEvent = window.attachEvent || window.addEventListener
      whichEvent = window.attachEvent ? "onbeforeunload" : "beforeunload";
      attachEvent(whichEvent, handleExit);
    }
}

function handleExit(e){
  client.trigger("exit");
}

// from superagent.js
function getXHR() {
    if (window.XMLHttpRequest && ('file:' != window.location.protocol || !window.ActiveXObject)) {
      return new XMLHttpRequest;
    } else {
      try { return new ActiveXObject('Microsoft.XMLHTTP'); } catch(e) {}
      try { return new ActiveXObject('Msxml2.XMLHTTP.6.0'); } catch(e) {}
      try { return new ActiveXObject('Msxml2.XMLHTTP.3.0'); } catch(e) {}
      try { return new ActiveXObject('Msxml2.XMLHTTP'); } catch(e) {}
    }
    return false;
}

setUnloadListener();

client.on("exit", function(){
  var request = getXHR();
  var url = client.url("/projects/"+client.projectId()+"/events/" + "visit");
  if (request) {
    url += "?api_key=" + client.writeKey();
    url += "&data=" + encodeURIComponent( Keen.Base64.encode( JSON.stringify( DataModel ) ) );
    request.open('GET', url, false);  // synchronous
    request.send(null);
  }
});

[dustinlarimer]

this is now possible in v3.2 by passing a fourth 'null' argument to addEvent(). just be sure to check the changelog for updates to the single callback pattern. thanks for suggesting this feature!

[dustinlarimer]

that's #addEvent ^ mobile typo :)

[caschoener]

It would be nice if this worked for addEvents() too