JSFiddle - React, Tailwind, and code Playground

HTML

<button id="btn">click me</button>

JavaScript

// get a cross-browser function for adding events, place this in [global] or somewhere you can access it
var on = (function(){
    if (window.addEventListener) {
        return function(target, type, listener){
            target.addEventListener(type, listener, false);
        };
    }
    else {
        return function(object, sEvent, fpNotify){
            object.attachEvent("on" + sEvent, fpNotify);
        };
    }
}());

var toggle = (function(){
    var state = false;
    return function(){
        state = !state;
        if (state) {
            alert("foo");
        }else{
            alert("bar");
        }
    };
})();

var btn = document.getElementById("btn");
on(btn, "click", toggle);