files/en-us/web/api/audioworkletnode/port/index.md
{{APIRef("Web Audio API")}}{{SecureContext_Header}}
The read-only port property of the
{{domxref("AudioWorkletNode")}} interface returns the associated
{{domxref("MessagePort")}}. It can be used to communicate between the node and its
associated {{domxref("AudioWorkletProcessor")}}.
[!NOTE] The port at the other end of the channel is available under the {{domxref("AudioWorkletProcessor.port", "port")}} property of the processor.
The {{domxref("MessagePort")}} object that is connecting the
AudioWorkletNode and its associated AudioWorkletProcessor.
To demonstrate bidirectional communication capabilities, we'll create an
AudioWorkletProcessor, which will output silence and respond to ping
requests from its AudioWorkletNode.
First, we need to define a custom AudioWorkletProcessor, and register it.
Note that this should be done in a separate file.
// ping-pong-processor.js
class PingPongProcessor extends AudioWorkletProcessor {
constructor(...args) {
super(...args);
this.port.onmessage = (e) => {
console.log(e.data);
this.port.postMessage("pong");
};
}
process(inputs, outputs, parameters) {
return true;
}
}
registerProcessor("ping-pong-processor", PingPongProcessor);
Now in our main scripts file we'll load the processor, create an instance of
AudioWorkletNode passing the name of the processor, and connect the node to
an audio graph.
const audioContext = new AudioContext();
await audioContext.audioWorklet.addModule("ping-pong-processor.js");
const pingPongNode = new AudioWorkletNode(audioContext, "ping-pong-processor");
// send the message containing 'ping' string
// to the AudioWorkletProcessor from the AudioWorkletNode every second
setInterval(() => pingPongNode.port.postMessage("ping"), 1000);
pingPongNode.port.onmessage = (e) => console.log(e.data);
pingPongNode.connect(audioContext.destination);
This will output "ping" and "pong" strings to the console
every second.
{{Specifications}}
{{Compat}}