Bug 141116 – Mousemove event is not firing as intended

• Component: DOM
• Status: RESOLVED FIXED

[Rob]

Created attachment 245781 [details]
CPU Profile of 12 image demo

I apologize in advance for not being able to determine the exact issue here, or provide a reduced test case.

Overview: Essentially, this is was found while using the jQuery AnythingZoomer plugin. There is a significant delay (2-3 seconds) that is introduced when trying to position a div containing more than 10 stacked images under the cursor; with 10 or less images the behavior is as expected. This issue does not occur in Firefox, Opera or IE11 (I didn't test in older IE versions).

Here is a demo of the plugin behaving as expected (10 images in large container): http://jsfiddle.net/5j354atc/3/
Here is a demo of the huge delay (12 images in large container): http://jsfiddle.net/5j354atc/2/

Steps to Reproduce:
1) Load the demo; there is an expected initialization delay of a second or two.
2) Move the mouse anywhere over the map.
3) Notice how long it takes for the zoom window to appear under the mouse.

Actual Results:
In the 12 image demo, I ran and profile and examined the flame graph (CPU profile attached). I noticed that jQuery was not receiving any mousemove events

[Rob]

Continued...

Expected Results:
The zoom window moves with the mouse cursor with minimal delay.

Build Date & Platform:
Version 40.0.2214.94 m on Windows 8.1 64bit

[Rob]

Sorry, I included the version of Chrome above; it was reported to me that this issue also occurs in Safari, which I don't have access to.

[Rob]

Update: The AnythingZoomer repository was moved under the CSS-Tricks organization, so the previous demos stopped working. Here are links pointing to the updated demos:

 8 image demo: http://jsfiddle.net/Mottie/5j354atc/8/
10 image demo: http://jsfiddle.net/Mottie/5j354atc/6/
12 image demo: http://jsfiddle.net/Mottie/5j354atc/7/

After updating these demos, it appears that the issue has gotten worse! I now see a big delay with 10 stacked images. This delay disappears (after about 2 seconds of mouse movement) when 8 images are stacked.

Again, there is no noticeable delay in Firefox even when using 12 stacked images.

[Rob]

This is no longer an issue... just tested in the latest versions of Chrome & Opera (no Safari on Windows).

[Lucas Forschler]

Mass move bugs into the DOM component.