JSFiddle - React, Tailwind, and code Playground

HTML

<div id="textarea" contenteditable="true">
  drag some content here!
</div>

<b>like this <i>text with some <span style="color:red;">wacky</span> styling</i></b>

CSS

#textarea{
  padding:10px;
  background:teal;
  color:#fff;
}

JavaScript

textarea = document.getElementById("textarea");

textarea.addEventListener("drop", function(event){
	
	event.preventDefault();
	let textBuffer = event.dataTransfer.getData("text/plain");
	
	textarea.addEventListener("focus", function(){
		console.log(document.activeElement, textBuffer);
    getSelection().collapse(textarea.firstChild || textarea, 0);
		document.execCommand(
			"insertText",
			false,
			textBuffer
		);
	}, {once: true});
		
	textarea.focus();
});