JSFiddle - React, Tailwind, and code Playground

JavaScript

var frame = document.createElement("iframe")
    frame.onload = function() {
      var frameWin = frame.contentWindow
      console.log(frameWin.location); // about:blank
      console.log(frameWin.location.origin); // "null"
      console.log(frameWin.origin); // "https://fiddle.jshell.net"
    }
    document.body.appendChild(frame);