Get Google Analytics ID with Javascript

Question

I am trying to extract the Google analytics ID from a html document.

I found the following function:

function get_UA() {

txt = document.getElementById('scripttag').value;

var matches = txt.match(/(UA-[\d-]+)/);

if (matches[1]) {

    alert(matches[1]);

}

}

But im getting this error:

TypeError: 'null' is not an object (evaluating 'document.getElementById('scripttag').value')

Any ideas?

Answer 1

Can you access the _gaq variable? If you can, and the page is using asynchronous tracking...

var accountId = _gaq._getAsyncTracker()._getAccount();

Answer 2

In April 2017, this works:

ga.getAll()[0].b.data.values[':trackingId']