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.
The visible state of a browser
<iframe> has nothing to do with its actual visibility (which is handled through CSS). The visible state is used to define the level of resources required by the browser
<iframe>. If the visible state is set to
true, it means that the browser
<iframe> should have high priority over the resources needed to render and handle its content. On the contrary, if its visible state is set to
false, it has low priority over the resources it needs.
As an example, if the content of a browser
<iframe> uses the
window.requestAnimationFrame method and if the visible state is set to
window.requestAnimationFrame will be called as often as necessary. However, if the visible state is set to
window.requestAnimationFrame will be called only when there are free resources to do it.
var browser = document.querySelector('iframe'); browser.setVisible(true);
Not part of any specification.