This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The RTCDataChannel property bufferedAmountLowThreshold is used to specify the number of bytes of buffered outgoing data that is considered "low." The default value is 0. When the number of buffered outgoing bytes, as indicated by the bufferedAmount property, falls to or below this value, a bufferedamountlow event is fired. This event may be used, for example, to implement code which queues more messages to be sent whenever there's room to buffer them. Listeners may be added with onbufferedamountlow or addEventListener().

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

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


var threshold = aDataChannel.bufferedAmountLowThreshold;

aDataChannel.bufferedAmountLowThreshold = threshold;


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


In this snippet of code, bufferedAmountLowThreshold is set to 64kB, and a handler for the bufferedamountlow event is established by setting the RTCDataChannel.onbufferedamountlow property to a function which should send more data into the buffer by calling send().

var dc = peerConnection.createDataChannel("File Transfer");
dc.bufferedAmountLowThreshold = 65535;

dc.onbufferedamountlow = function() {
  /* use send() to queue more data to be sent */


Specification Status Comment
WebRTC 1.0: Real-time Communication Between Browsers
The definition of 'RTCDataChannel.bufferedAmountLowThreshold' in that specification.
Candidate Recommendation Initial specification.

Browser compatibility

ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Chrome Full support 56Edge Full support ≤79Firefox Full support YesIE No support NoOpera Full support 43Safari Full support YesWebView Android Full support 56Chrome Android Full support 56Firefox Android No support NoOpera Android Full support 43Safari iOS No support NoSamsung Internet Android Full support 6.0


Full support
Full support
No support
No support
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.

See also