iframe cross domain

test.js

// from parent javascript would be

window.addEventListener('message', function(event){
    // event handle
    console.log(event)
})
// use button click to send event 'test' could be anything
function send(){
    let iframe = window.frames[0];
    iframe.postMessage('test', document.querySelector('iframe').src);
}


// from child iframe usage

window.addEventListener('message', function(event){
    // Can recording the event.source and do postMessage to the parent window
    console.log(event.origin);
    event.source.postMessage('test','http://localhost:8080');
})