Fix always scroll to top issue on IE 7

[chrisyip]

When the container is "window" and event is "scroll", will cause window to scroll back to top on IE 7.

The reason is

// settings.container = window
// settings.event = "scroll"
$(settings.container).trigger(settings.event);

works as the below code on IE 7:

`window.scrollTo(0, 0);``

Also, I cached window object to improve performance.

[tuupola]

I cannot merge this patch cleanly anymore since there have been quite many changes. But I am doing it manually. Great patch! Short scoping and caching the window object almost doubles the selector speed.

http://jsperf.com/lazyload-1-6-0
http://jsperf.com/lazyload-1-7-0

[tuupola]

Do you still experience the IE7 bug also with latest jQuery? To me it looks like it was fixed in 1.7.

http://bugs.jquery.com/ticket/6170

[chrisyip]

Maybe latest jQuery fixed this issue, but for some frameworks, e.g. Drupal 6, you can't simply update jQuery to latest one, that's why I fix this issue, and this issue is easy to fix :-)

About the performance of copying window, on my Chrome 16.0.912.75 on Mac OS X 10.7.2, it's faster than don't copy.
In fact, I was just wanna pull request for the IE 7 issue, not the performance or something else :/
Coz I'm customizing it to fit our Drupal project.
Just Forget about it.

[tuupola]

That is interesting. I just tested Chrome 16.0.912.75 on Mac OS X 10.7.2 and I get around 4600 ops / second when copying and 7200 ops / second when caching.

Anyway, what version of jQuery Drupal 6 is using?

[chrisyip]

Drupal 6 is using 1.2.6 for core library (WTF?!), with a third-part module, can be upgraded to 1.3.2.
In the past, I tried to upgrade to 1.5.2 (or lower), and lots of core features were broken.
Although I can load latest jQuery with $.noConflict() and initialize lazyload with it.

[ssorallen]

The issue affects even jQuery 1.7 as far as I can tell. Try scrolling to the bottom of http://www.ea.com/ and executing jQuery(window).trigger('scroll'), which is what happens in this plugin's resize listener by default. That call scrolls the page to the top.

[ssorallen]

Example: scroll to the bottom of your project page, http://www.appelsiini.net/projects/lazyload, and then resize the window. It scrolls to the top.

Edit: I'm on OS X, Chrome 17.0.963.56

[tuupola]

Actually project page has 1.6. Demo pages have 1.7.

http://www.appelsiini.net/projects/lazyload/enabled_fadein.html

But since many people are still using 1.6 and older I might consider including Chris' workaround for Chrome.

[ssorallen]

I noticed the 1.6/1.7 difference right after I wrote my comments. The workaround doesn't seem ideal, calling $window.scrollTo with the current coordinates.