RTCDTMFToneChangeEvent: tone property

The read-only property RTCDTMFToneChangeEvent.tone returns the DTMF character which has just begun to play, or an empty string (""). if all queued tones have finished playing (that is, RTCDTMFSender.toneBuffer is empty).

Value

A string with the DTML character playing, or the empty string.

Example

This example establishes a handler for the tonechange event which updates an element to display the currently playing tone in its content, or, if all tones have played, the string "<none>".

js
dtmfSender.ontonechange = (ev) => {
  let tone = ev.tone;
  if (tone === "") {
    tone = "&lt;none&gt;";
  }

  document.getElementById("playingTone").innerText = tone;
};

Specifications

Specification
WebRTC: Real-Time Communication in Browsers
# dom-rtcdtmftonechangeevent-tone

Browser compatibility

Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
tone

See also