User opt-out with gtag.js

Question

We're looking to implement the option for our website visitors to disable tracking.

I've read the Google Analytics opt-out dev guide but I'm still not totally clear on how to do this.

Is it sufficient to just trigger window['ga-disable-GA_TRACKING_ID'] = true; when a button is clicked?

Will Google Analytics remember the setting for this user, or is it on a per-visit basis?

Can the user re-enable tracking if I have a second button that sets it to false?

Answer 1

Paste the following into the head tag before the Analytics code (replacing the UA with your own UA)

<script>
// Set to the same value as the web property used on the site
var gaProperty = 'UA-XXXX-Y';

// Disable tracking if the opt-out cookie exists.
var disableStr = 'ga-disable-' + gaProperty;
if (document.cookie.indexOf(disableStr + '=true') > -1) {
  window[disableStr] = true;
}

// Opt-out function
function gaOptout() {
  document.cookie = disableStr + '=true; expires=Thu, 31 Dec 2099 23:59:59 UTC; path=/';
  window[disableStr] = true;
}
</script>

And use this to trigger it:

<a href="javascript:gaOptout()">Click here to opt-out of Google Analytics</a>