SourceBuffer: textTracks property
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
Note: This feature is available in Dedicated Web Workers.
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The textTracks read-only property of the
SourceBuffer interface returns a list of the text tracks currently
contained inside the SourceBuffer.