JSFiddle - React, Tailwind, and code Playground

HTML

<div contenteditable="true" id="content_editable_div">
  <div id="first_div">
    First Div
  </div>
  <div id="second_div">
    Second Div
  </div>
</div>

CSS

* {font-family: "monospace"; font-size:10pt;}
.output {color: #c00;}

JavaScript

$(document).ready(function () {

    function onMouseUp(e) {
        console.log(this.id);
        alert(this.id);
    }

    document.getElementById("first_div").addEventListener("mouseup", onMouseUp, false);
    document.getElementById("second_div").addEventListener("mouseup", onMouseUp, false);
});