JSFiddle - React, Tailwind, and code Playground

HTML

<button onclick="_sendMessage ()">Send</button>
<iframe src="" id="myIframe">

JavaScript

var myIframe = document.getElementById('myIframe');
myIframe.contentWindow.addEventListener('message', function(event) {
    console.log(JSON.parse(event.data));
}, false);


window._sendMessage = function() {
    var json = {payload:'Hello World'};
    myIframe.contentWindow.postMessage(JSON.stringify(json), '*');
}