[whatwg] Deferring image load

[Boris Zbarsky]

On 2/13/12 1:39 AM, Gray Zhang wrote:
>     1. the @defer attribute on<img>  and<iframe>
>     2. the similar @deferpolicy attribute with value a combination of visible,
>     network-idle and render-idle
>     3. a global switch as a http header or an attribute on html to switch
>     UAs image loading from "obtain images immediately" to "obtain on demand" or
>     vice versa.
>     4. onscrollintoview/onscrolloutofview events
>     5. DOMVisibilityChanged event

#4 and #5 are conceptually no better than onscroll plus position 
calculations, right?

I prefer #1 and/or #2 to #3, because it gives the UA strictly more 
information to use in prioritizing the image loads....

-Boris