AudioWorkletNode.port

The read-only port property of the AudioWorkletNode interface returns the associated MessagePort. It can be used to communicate between the node and its associated AudioWorkletProcessor.

Syntax

audioWorkletNodeInstance.port;

Value

The MessagePort object that is connecting the AudioWorkletNode and its associated AudioWorkletProcessor.

Examples

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 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

Browser compatibility

See also

• Web Audio API
• Using the Web Audio API