JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <div id="asdf">
        <p id="outer"></p>
    </div>
    <script>
        var insert = document.createElement('div');
        var text = document.createTextNode('ladygaga');
        insert.appendChild(text);
        document.getElementById('outer').appendChild(insert);


        var elem = document.getElementById("asdf");
        var r = document.querySelectorAll("[id=outer] ~ *");
        for (var i = 0; i < r.length; ++i) {
            elem.removeChild(r[i])
        }
    </script>
</body>

JavaScript

var e = document.getElementById('asdf');
var html = e.outerHTML;
console.log(document.body.outerHTML);

var blob = new Blob([document.body.outerHTML], {
    type: "text/html"
});

var objUrl = window.URL.createObjectURL(blob);

var popup = window.open(objUrl, "popup", "width=300, height=200");