Obsolete
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.
  Non-standard
 
      This feature is not on a current W3C standards track, but it is supported on the Firefox OS platform. Although implementations may change in the future and it is not supported widely across browsers, it is suitable for use in code dedicated to Firefox OS apps.
The mozbrowserasyncscroll event is fired when the content of a browser <iframe> is scrolled.
General info
- Specification
 - Non standard
 - Interface
 CustomEvent- Bubbles
 - Yes
 - Cancelable
 - Yes
 - Target
 <iframe>- Default Action
 - None
 
Properties
| Property | Type | Description | 
|---|---|---|
target Read only  |  
    EventTarget |  
    The browser iframe | 
type Read only  |  
    DOMString |  
    The type of event. | 
bubbles Read only  |  
    boolean |  
    Does the event normally bubble? | 
cancelable Read only  |  
    boolean |  
    Is it possible to cancel the event? | 
details Read only  |  
    object |  
    A custom object | 
details
The details property returns an anonymous JavaScript object with the following properties:
top- The scroll top position in CSS pixels of the document within the browser 
<iframe>. left- The scroll left position in CSS pixels of the document within the browser 
<iframe>. width- The width in CSS pixels of the visible part of the document within the browser 
<iframe>. height- The height in CSS pixels of the visible part of the document within the browser 
<iframe>. scrollWidth- The total content width in CSS pixels of the document within the browser 
<iframe>. scrollHeight- The total content height in CSS pixels of the document within the browser 
<iframe>. 
Note: top + height may be larger than scrollHeight. This indicates that the content is over-scrolled, which occurs when the page "rubber-bands" after being scrolled all the way to the bottom. Similarly, left + width may be greater than scrollWidth, and both left and top may be negative.
Note: For performance reasons, this event is asynchronous. That means that the value retrieved through the event object can be different than the real current position of the scroll when the event is processed.
Examples
var browser = document.querySelector("iframe");
browser.addEventListener("mozbrowserasyncscroll", function( event ) {
  console.log("The scroll top position of the document is:" + event.details.top + "px");
});
Related Events
mozbrowserclosemozbrowsercontextmenumozbrowsererrormozbrowsericonchangemozbrowserloadendmozbrowserloadstartmozbrowserlocationchangemozbrowseropenwindowmozbrowsersecuritychangemozbrowsertitlechangemozbrowserusernameandpasswordrequired