JSFiddle - React, Tailwind, and code Playground

HTML

<body>
<button id="testBtn">Test</button>
</body>

JavaScript

function TestUIElem() {
  this.elem = null;
}
TestUIElem.prototype = {
  activate: function () {
    this.elem = document.querySelector('button#testBtn');
    this.elem.addEventListener('click', this, false);
  },
  click: function () {
    alert('test');
    this.deactivate();
  },
  deactivate: function () {
    this.elem.removeEventListener('click', this);
  },
  handleEvent: function(event){
    switch(event.type){
      case 'click':
      this.click(event);
      break;
    }
  }
};

testUIElem = new TestUIElem();
testUIElem.activate();