JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://html2canvas.hertzen.com/build/html2canvas.js"></script>

JavaScript

var html_string = "<html><head></head><body><p>HI</p></body></html>";
var iframe=document.createElement('iframe');
document.body.appendChild(iframe);
setTimeout(function(){
    var iframedoc=iframe.contentDocument||iframe.contentWindow.document;
    iframedoc.body.innerHTML=html_string;
    html2canvas(iframedoc.body, {
        onrendered: function(canvas) {
            document.body.appendChild(canvas);
            document.body.removeChild(iframe);
        }
    });
}, 10);