getConstraints method
The getConstraints() method of
the MediaStreamTrack interface returns a
MediaTrackConstraints object containing the set of constraints most
recently established for the track using a prior call to
MediaStreamTrack.applyConstraints. These
constraints indicate values and ranges of values that the website or
application has
specified are required or acceptable for the included constrainable
properties.
Constraints can be used to ensure that the media meets certain guidelines you prefer. For example, you may prefer high definition video but require that the frame rate be a little low to help keep the data rate low enough not overtax the network. Constraints can also specify ideal and/or acceptable sizes or ranges of sizes. See Capabilities, constraints, and settings for details on how to work with constrainable properties.
Implementation
external MediaTrackConstraints getConstraints();