MessageChannel: port1 property
The port1
read-only property of the
MessageChannel
interface returns the first port of the message channel —
the port attached to the context that originated the channel.
Note: This feature is available in Web Workers
Value
A MessagePort
object, the first port of the channel, that is the port
attached to the context that originated the channel.
Examples
In the following code block, you can see a new channel being created using the
MessageChannel()
constructor. When the
<iframe>
has loaded, we pass MessageChannel.port2
to the
<iframe>
using MessagePort.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. The handleMessage
method is associated to the
port1
to listen when the message arrives.
js
const channel = new MessageChannel();
const para = document.querySelector("p");
const ifr = document.querySelector("iframe");
const 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;
}
Specifications
Specification |
---|
HTML Standard # dom-messagechannel-port1-dev |
Browser compatibility
BCD tables only load in the browser