JSFiddle - React, Tailwind, and code Playground

HTML

<div>Some default text; HUlk is very cool innit</div>
<br/>

<input type="text" id="hulk" />

JavaScript

function selHTML() {

    try {
        if (window.ActiveXObject) {
            var c = document.selection.createRange();
            return c.htmlText;
        }

        var nNd = document.createElement("span");
        var w = getSelection().getRangeAt(0);
        w.surroundContents(nNd);
        return nNd.innerHTML;
    } catch (e) {
        if (window.ActiveXObject) {
            return document.selection.createRange();
        } else {
            return getSelection();
        }
    }
    
}


$(function() {

    $(document).bind("mouseup", function() {
        var mytext = selHTML();
        $('#hulk').val(mytext);
        alert("selected text is ==> " + mytext);
    });

});