This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
- A floating point number representing the volume you want to set — this can have a value between 0 and 1.
var browser = document.querySelector('iframe'); browser.setVolume(0.5);
Not part of any specification.