files/en-us/web/api/messageport/start/index.md
{{APIRef("Channel Messaging API")}} {{AvailableInWorkers}}
The start() method of the {{domxref("MessagePort")}}
interface starts the sending of messages queued on the port. This method is only needed
when using {{domxref("EventTarget.addEventListener")}}; it is implied when using
{{domxref("MessagePort.message_event", "onmessage")}}.
start()
None.
None ({{jsxref("undefined")}}).
In the following code block, you can see a handleMessage handler function,
run when a message is sent back to this document using onmessage:
channel.port1.onmessage = handleMessage;
function handleMessage(e) {
para.innerHTML = e.data;
}
Another option would be to do this using {{domxref("EventTarget.addEventListener")}},
however, when this method is used, you need to explicitly call start() to
begin the flow of messages to this document:
channel.port1.addEventListener("message", handleMessage);
function handleMessage(e) {
para.innerHTML = e.data;
textInput.value = "";
}
channel.port1.start();
{{Specifications}}
{{Compat}}