1605800 - Load event doesn't always fire

Status: RESOLVED INVALID

(Core :: DOM: Core & HTML, defect)

Description

[luke32j]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:71.0) Gecko/20100101 Firefox/71.0

Steps to reproduce:

The background does not show on https://www.fccbillerica.org/ because the detection of load does not always happen for images, but it works fine on other browsers.
For example you can see at http://jsfiddle.net/8c42a3tn the alert does not pop up.
On one install on one computer, it is working on fccbillerica and when I click run on that jsfiddle it does show the alert('loaded').

Actual results:

Firefox doesn't let scripts know an image loaded in some circumstances, where other browsers are working.

Expected results:

Load event should happen on load.

Comment 1

[Seba S.]

Attachment: fccbillerica.png

Comment 2

[Seba S.]

Hi, luke32j!

Thanks for your contribution!

I could reproduce the described behavior in:

Windows 10 and Ubuntu 18.0.4
Firefox Nightly 73.0a1 (2019-12-30) (64-bit)
Firefox 71.0

I'll add product and component to this issue so we can keep working on it.

Regards,

Comment 3

[Olli Pettay [:smaug][[e-mail]]]

The test is racy. Image may have been loaded already before the load event listener is added to the img element.
Can you reproduce with http://jsfiddle.net/cbnmj4xt/ (I can't) ?

Please reopen if I'm missing something here.

Comment 4

[luke32j]

I should note that although this was an issue with WP Rocket plugin, the issue seemingly only happened on Firefox. So may possibly be a bug or inconsistency.
Site does not have an issue now so you can close this bug thank you.