This snippet will anonymize IP addresses for Google Analytics (Universal, analytics.js) unless a cookie eucookieconsent is set with value 1.You wil need to put this in the top of the head of your website, or at leaset BEFORE analytics is loaded.

anonymizeIp-google-analytics-unless-consent.js

(function(t,r,a,c,k,i,n,g) {
  if (c === n.test(g)) return;
  t[r]=t[r]||function(){(t[r].q=t[r].q||[]).push(arguments); if (arguments[0] == i) { t[r]("set", k, c); }};
  t[a]=t[a]||t[r];
})( window, 'ga', '__gaTracker', !0, 'anonymizeIp', 'create', /eucookieconsent=1/, document.cookie );