Update jQuery to 1.4.2

[xibe]

Following up with ​the jQuery UI upgrade, the jQuery team just updated the framework itself, ​with some more improvements, most notably performance-wise.

[Viper007Bond]

It's apparently like twice as fast as 1.4.1. Worth including.

[ryan]

(In [13310]) jQuery 1.4.2. fixes #12305

[ianatkins]

Can I recommend linking to the Google ajax hosted version of Jquery. It has proper header compression, reducing the filesize. And as the library is linked elsewhere there is an increased chance that the file will be locally cached.

[nacin]

Those who run local or intranet installs wouldn't like that so much.

There is a plugin (or five) available that unregisters the default jQuery and registers it with the source pointing to Google.

[ianatkins]

Good point. I'm guessing that running WP locally isn't the majority case. Be nice if we served the majority, and perhaps tested for local running, or had a check box in the settings page.

Perhaps this is a debate to be had on the forum..
​http://wordpress.org/support/topic/387476

Replying to nacin:

Those who run local or intranet installs wouldn't like that so much.

There is a plugin (or five) available that unregisters the default jQuery and registers it with the source pointing to Google.

[Viper007Bond]

I can tell you right now we'd get a small revolt if we switched to Google or Yahoo hosted jQuery due to perceived (or even real) privacy concerns.

Not to mention that WordPress already compresses it itself. It merges all Javascript files together and serves them as one compressed HTTP request. This is much better than serving it off Google or Yahoo.