how to get the Google analytics client ID

When you are creating a new instance of analytics.js by running

ga('create', 'UA-XXXXXXX-Y', {'cookieDomain': 'none'});

GA creates a unique client Id. I want to fetch this id and use it for my own purposes, but I can find only setter for this parameter but can't find any getter method to get it.

GA send it later in a parameter called &cid=123123.232323

Does anyone knows how do I get it?

Google does have some documentation on getting the client id.

Looks like this:

ga(function(tracker) {
  var clientId = tracker.get('clientId');
});

I've used this before, too:

ga.getAll()[0].get('clientId');

EDIT: If you have more than one tracker on the page, it may be probable that at index 0 there is not the one you want, so an alternative function should be the following:

function() {
  try {
    var trackers = ga.getAll();
    var i, len;
    for (i = 0, len = trackers.length; i < len; i += 1) {
      if (trackers[i].get('trackingId') === "ID-PROPERTY") {
        return trackers[i].get('clientId');
      }
    }
  } catch(e) {}  
  return 'false';
}

where ID-PROPERTY is the id of your Property (i.e. UA-XXXXX-XX).