Extracts the container subtype from a MIME type, lowercased — the portion after the /, ignoring any parameters. For example video/webm; codecs="vp9" → webm and audio/mp4 → mp4. Returns an empty string when the MIME type has no subtype.
/
video/webm; codecs="vp9"
webm
audio/mp4
mp4
Extracts the container subtype from a MIME type, lowercased — the portion after the
/, ignoring any parameters. For examplevideo/webm; codecs="vp9"→webmandaudio/mp4→mp4. Returns an empty string when the MIME type has no subtype.