RTCDataChannel: bufferedAmountLowThreshold property

BaselineWidely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.

TheRTCDataChannel propertybufferedAmountLowThreshold is used to specify the numberof bytes of buffered outgoing data that is considered "low." The default value is0. When the number of buffered outgoing bytes, as indicated by thebufferedAmount property, falls to orbelow this value, abufferedamountlow event is fired. This event may beused, for example, to implement code which queues more messages to be sent wheneverthere's room to buffer them. Listeners may be added withonbufferedamountlow oraddEventListener().

The user agent may implement the process of actually sending data in any way itchooses; this may be done periodically during the event loop or truly asynchronously. Asmessages are actually sent, this value is reduced accordingly.

Note:bufferedamountlow events are not fired after the data channel is closed.

Value

The number of queued outgoing data bytes below which the buffer is considered to be"low."

Example

In this snippet of code,bufferedAmountLowThreshold is set to 64kB, and ahandler for thebufferedamountlow event is established by setting theonbufferedamountlow property to a function which shouldsend more data into the buffer by callingsend().

const dc = peerConnection.createDataChannel("File Transfer");dc.bufferedAmountLowThreshold = 65535;dc.onbufferedamountlow = () => {  /* use send() to queue more data to be sent */};