RTCDataChannel: bufferedamountlow event

A bufferedamountlow event is sent to an RTCDataChannel when the number of bytes currently in the outbound data transfer buffer (bufferedAmount) falls from above to below or equal the threshold specified in bufferedAmountLowThreshold.

This event is not cancelable and does not bubble.

Syntax

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

addEventListener("bufferedamountlow", (event) => { })

onbufferedamountlow = (event) => { }

Event type

A generic Event.

Examples

This example sets up a handler for bufferedamountlow to request more data any time the data channel's buffer falls below the number of bytes specified by bufferedAmountLowThreshold, which we have set to 65536. In other words, we'll try to keep at least 64kB of data in the buffer, reading 64kB at a time from the source.

let pc = new RTCPeerConnection();
let dc = pc.createDataChannel("SendFile");
// Replace with your own source object, such as a file handle
let source = null;
dc.bufferedAmountLowThreshold = 65536;

pc.addEventListener(
  "bufferedamountlow",
  (ev) => {
    if (source.position <= source.length) {
      dc.send(source.readFile(65536));
    }
  },
  false,
);

After creating the RTCPeerConnection, this calls RTCPeerConnection.createDataChannel() to create the data channel. Then a listener is created for bufferedamountlow to refill the incoming data buffer any time its contents fall below 65536 bytes.

You can also set up a listener for bufferedamountlow using its event handler property, onbufferedamountlow:

pc.onbufferedamountlow = (ev) => {
  if (source.position <= source.length) {
    dc.send(source.readFile(65536));
  }
};

Specifications

Browser compatibility

See also

• WebRTC API
• RTCDataChannel
• RTCDataChannel.bufferedAmountLowThreshold