JSFiddle - React, Tailwind, and code Playground

HTML

<button type="button">Click me!</button>

JavaScript

(function(){
    'use-strict';
    
    var button = document.getElementsByTagName('button')[0];
    var myHandler = function() {
        var click = 0;
        return function() {
            if(click === 0) {
                alert('single click');
            }
            click++;
        }
    }();
    
    
    button.addEventListener('click', myHandler, false);
})();