Emoji: JavaScript error in Internet Explorer 9 and 10

[germozy]

There is a javascript error in wp-includes/js/twemoji.min.js. The problem appears in Internet Explorer 9 and 10.
Unable to get property 'childNodes' of undefined or null reference.

​http://fs2.directupload.net/images/150424/77zoplfe.png

[peterwilsoncc]

Ensure document.body is defined

[peterwilsoncc]

Looks like wp-emoji.js was passing document.body to be parsed before it existed.

Per discussion in slack, I've changed the IE8 check to for IE8, IE9 or IE10.

As a fail safe, in the looping waiting for twemoji to load, I've added a check that document.body is defined.

[azaozz]

32109.1.diff changes all IE < 11 to wait for body.onload which can fire much later if there is a slow loading image, etc.

A better solution seems to be to use DOMContentLoaded which is supported everywhere except IE < 9. Then keep document.readyState === 'complete' for IE8. For this we will need to set a var in case DOMContentLoaded fires before twemoji.js is loaded (unlikely but possible).

[azaozz]

In 32109.2.diff:

• Use DOMContentLoaded to initialize wp-emoji.
• Use readystatechange and document.readyState === 'complete' as fallback in case DOMContentLoaded is not supported (IE < 9 and other really outdated browsers).

Tested in Firefox, Chrome, IE11, IE8. Needs testing in IE10 and 9 just in case, and perhaps in other obscure browsers if somebody has one handy.

[peterwilsoncc]

WFM on BrowserStack instances of:
Win7/IE10
Win7/IE9
Win7/FF3.6
Win7/Old Safaris and Operas

Win8/IE10
Win8/IE10metro

[azaozz]

In 32109.3.diff: use the same events as jQuery( document ).ready() (the compat branch).

Tested in Firefox, Chrome, IE11 and 8. Still good to test in native/not-emulated browsers.

[azaozz]

In 32334:

Emoji:

• Fix loading errors in IE9 and IE10.
• Add fallbacks for the loading events.

Fixes #32109 for trunk.

[azaozz]

Reopen for 4.2.

[pento]

#32252 was marked as a duplicate.

[azaozz]

In 32361:

Emoji:

• Fix loading errors in IE9 and IE10.
• Add fallbacks for the loading events.

Fixes #32109 for 4.2.

[jobst]

I initially reported this as #32252.
Just installed latest wordpress 4.2.2 on my life sites.
Tested it in IE10 - I do not get those errors anymore - thanks for fixing this, and including the debugging for the wp-emoji ;-)
Jobst