window.addEventListener('message', function(e) { if(e.data == 'minimizeIframe') { iframe = document.getElementById("customer-chat-iframe") iframe.style.height="50px"; iframe.contentWindow.postMessage("scrollChat", "*"); } if(e.data == 'maximizeIframe') { iframe = document.getElementById("customer-chat-iframe") iframe.style.height="470px"; iframe.contentWindow.postMessage("scrollChat", "*"); } });