JSFiddle - React, Tailwind, and code Playground

HTML

<button id="one">List View</button>
<button id="two">Calendar View</button>
<iframe id="iframe" src="http://graceinauburn.com/upcoming-events-list-view/" frameborder="0" width="100%" height="1300px"></iframe>

JavaScript

var buttonOne = document.getElementById("one");
var buttonTwo = document.getElementById("two");
var iframe = document.getElementById("iframe");

buttonOne.addEventListener("click", buttonClick, false);
buttonTwo.addEventListener("click", buttonClick, false);

function buttonClick(e){
    if(e.target.id === "one"){
        iframe.src = "http://graceinauburn.com/upcoming-events-list-view/";
    }else{
        iframe.src = "http://graceinauburn.com/upcoming-events-calendar-view/";
    } 
};