MessagePort.postMessage()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since setembro de 2015.

O método postMessage() da interface MessagePort envia uma mensagem da porta e opcionalmente transfere a propriedade do objeto para outros contexto de navegação.

Nota: This feature is available in Web Workers.

Syntax

port.postMessage(message, transferList);

Parameters

message

A mensagem que você quer enviar atravéz do canal. Esta mensagem pode ser de qualquer tipo de dados basico. Multiplos items podem ser enviados com diferentestes tipos de dados como em um Array.

transferList Optional

Transferable objects to be transferred — these objects have their ownership transferred to the receiving browsing context, so are no longer usable by the sending browsing context.

In the following code block, you can see a new channel being created using the MessageChannel.MessageChannel constructor. When the IFrame has loaded, we pass MessageChannel.port2 to the IFrame using window.postMessage along with a message. The handleMessage handler then responds to a message being sent back from the IFrame using onmessage, putting it into a paragraph — MessageChannel.port1 is listened to, to check when the message arrives.

js
var channel = new MessageChannel();
var para = document.querySelector("p");

var ifr = document.querySelector("iframe");
var otherWindow = ifr.contentWindow;

ifr.addEventListener("load", iframeLoaded, false);

function iframeLoaded() {
  otherWindow.postMessage("Hello from the main page!", "*", [channel.port2]);
}

channel.port1.onmessage = handleMessage;
function handleMessage(e) {
  para.innerHTML = e.data;
}

For a full working example, see our channel messaging basic demo on Github (run it live too).