JSFiddle - React, Tailwind, and code Playground

HTML

<span>hhkjahsdkfasdfgasdg</span>
<button id="test">click</button>

JavaScript

$('#test').click(function(){
    var obj = document.getSelection();
    var parentNode = $(obj.anchorNode).parent();
    console.log(obj);
    alert(parentNode.text());
});