This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

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 (meaning no bufferedamountlow events are sent). 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.
Working Draft Initial specification.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 46 44 (44) [1] No support (Yes) ?
Feature Android Webview Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support 46 46 44.0 (44) [1] No support ? ?

[1] The interface is called DataChannel and not RTCDataChannel in Firefox; however, a binding was added in Firefox 24 so that either name may be used.

See also

Document Tags and Contributors

 Last updated by: jpmedley,