RTCDTMFSender: tonechange event

The tonechange event is sent to an RTCDTMFSender by the WebRTC API to indicate when DTMF tones previously queued for sending (by calling RTCDTMFSender.insertDTMF()) begin and end.

To determine what tone started playing, or if a tone stopped playing, check the value of the event's tone property.

This event is not cancelable and does not bubble.

Syntax

Use the event name in methods like addEventListener(), or set an event handler property.

js
addEventListener("tonechange", (event) => { })

ontonechange = (event) => { }

Event type

An RTCDTMFToneChangeEvent. Inherits from Event.

EventRTCDTMFToneChangeEvent

Examples

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>".

This can be done using addEventListener():

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

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

You can also just set the ontonechange event handler property directly:

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

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

Specifications