title: How to wait for all values in window.performance.timing are defined
body: <p>Currently I read the values in <code>window.performance.timing</code> within a <code>window.addEventListener('load', function () {...})</code> function. however in safari there are values like <code>loadEventEnd</code> still being set to <code>0</code>.</p>
  
  <p>How to delay my call to <code>window.performance.timing</code> in the best way event based until this and other values are defined?</p>