Run results for: ownerDocument.defaultView vs window.getComputedStyle

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 12_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/16A5327f

Browser: Mobile Safari 12

Operating system: iOS 12.0

Device Platform: Mobile

Date tested: 5 years ago

Test name	Executions per second
ownerDocument.defaultView	1134157.0 Ops/sec
window.getComputedStyle	1579261.0 Ops/sec

HTML Preparation code:

<div id="root"><div>

Script Preparation code:

var el = document.getElementById("root");
function getStyle(elem){
  var view = elem.ownerDocument.defaultView;
  if ( !view || !view.opener ) {
    view = window;
  }

  return view.getComputedStyle( elem );
}

function getStyle2(elem){
  return window.getComputedStyle( elem );
}

Tests:

ownerDocument.defaultView
var computedStyle = getStyle(el);
window.getComputedStyle
var computedStyle = getStyle2(el);