1407013 - Lazy loading of images not working in reader view

Status: RESOLVED INVALID

(Toolkit :: Reader Mode, defect)

Description

[Amiad]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:57.0) Gecko/20100101 Firefox/57.0
Build ID: 20171005195903

Steps to reproduce:

I working reader view in page with lazy loading of images (example: http://runpanel.co.il/p/38460)


Actual results:

The images not loading.


Expected results:

The images loading.

Comment 1

[:Gijs (he/him)]

We can't fix this. The page uses JS to change the 'src' attribute of the images in question, and that JS isn't run in Reader Mode (and that's intentional, and not something we want to change - we can't control what kind of JS runs). To allow the site to have a better experience in reader mode, it could consider either removing the 'src' attribute later (so that the markup sent did include the correct src attributes) or ensuring that instead of a blank 1x1 pixel png data URI the src attribute was set to a smaller-size dummy image, or using visibility:hidden to avoid the src loading prior to the user scrolling to that position... there's a number of options.

Comment 2

[Martijn]

Just ran into this issue as well.
Firefox could limit the extent of javascript's capabilities in reader view.

Since lazy loading images is so common these days, not having the images show up at all is really just flushing reader view down the drain, because it becomes pretty much pointless.

Sending a correct src attribute down the line is not an option. This would defeat the whole purpose of lazy loading. I think we both know that if you do this, Firefox will starting loading every image on the page, possibly well before javascript kicks in. To do that just to accommodate reader view, is unacceptable.

Comment 3

[Martijn]

Can we have an event that fire just before the browser switches to reader view? That way we can "unlazy" the images so that reader view will work as intended.

Comment 4

[Martijn]

I just noticed beforeprint. That could fire before reader view becomes active. It is kinda-sorta like printing.