The timestamp read-only property of the EncodedAudioChunk interface returns an integer indicating the timestamp of the audio in microseconds.

An integer.

In the following example the timestamp is printed to the console.

const init = {
  type: "key",
  data: audioBuffer,
  timestamp: 23000000,
  duration: 2000000,
};
chunk = EncodedAudioChunk(init);

console.log(chunk.timestamp); //23000000