JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/ui-lightness/jquery-ui.css">

JavaScript

var varWithDOM = 
    '<!DOCTYPE html>\
    <html>\
        <head><title>the title</title></head>\
        <body><a>anchor</a></body>\
    </html>';


 // create and append new iframe
var iframe = document.createElement('iframe');
document.documentElement.appendChild(iframe);

  // set its innerHTML
iframe.contentWindow.document.documentElement.innerHTML = varWithDOM;

  // grab the `window`
var win = iframe.contentWindow;

  // remove the iframe
document.documentElement.removeChild(iframe);

console.log( win.document.head );