JSFiddle - React, Tailwind, and code Playground

HTML

<textarea>Some text</textarea>
<textarea>Some text more text</textarea>
<div></div>
<p>Some random text on the page</p>

JavaScript

var selectedTextarea = "";

$("textarea").select(function() {
    selectedTextarea = getSelectedText();
    $("div").text(selectedTextarea);
});

$("textarea").on("blur focus keydown mousedown", function() { 
    if(selectedTextarea.length > 0){
        $("div").text("");
        selectedTextarea = "";
    } 
});

function getSelectedText()
{
    var txt = "";
    var textComponent = document.getElementById('Editor');
    if (window.getSelection)
    {
        txt = window.getSelection(); 
        //for FF
        if (document.activeElement.nodeName == "TEXTAREA"){
            ta = document.activeElement;
            txt = ta.value.substring(ta.selectionStart, ta.selectionEnd);
        }            
    }
    else if (document.getSelection)
    {
        txt = document.getSelection();        
    }
    else if (document.selection)
    {
        txt = document.selection.createRange().text;
    }
    else if (textComponent.selectionStart != undefined)
  {
    var startPos = textComponent.selectionStart;
    var endPos = textComponent.selectionEnd;
    txt = textComponent.value.substring(startPos, endPos);
  }

  return txt.toString();
}