Since the Bootstrap folks have decided to promote Bootstrap 3 RC1 as their default version, I decided to use it to upgrade my site. Along the way I chose to finally fix the responsive layout issues I’ve had since, supposedly, Bootstrap 3 does the whole responsive thing far better than Bootstrap 2 did.
This pull request contains a good summary of the changes, so I won’t renumerate them blindly here; but be sure to check them out. I will review some things to keep in mind, however.
The grid system has been changed completely. The class names are totally different, and they behave differently now too; especially when considering responsiveness. You really should consider revisiting all of your site scaffolding, as directly porting over may not do as you expect.
That said, if you were using ~unresponsive~ Bootstrap, the closest migration is to use
col-# col-lg-# everywhere you previously had
span#. This tells Bootstrap to use the same gridding for both the smallest and largest devices.
I fought the new model for a while, and I suspect you might too, but once you can understand it, it can be quite powerful.
Aside from the obvious color changes, buttons no longer fallback to default styling when left as just “btn”. You need to now say “btn-default” if you have nothing else. Yes, this will probably require Regex to find on your site everywhere.
Other Responsive Details
There is now a whole series of “responsive” utilty classes that allow you to show/hide different page elements depending on certain page layouts. This is useful for those cases where the natural responsive re-flow is just not cutting it. Examples include
visible-sm (only show this element on the smallest container model), and
hidden-lg (show this on all but the largest/desktop container model).
The form system now uses 100% of the parent container. This is a significant change from Bootstrap 2, and will impact you in a non-trivial way. Most forms will have to be revisited entirely. For example, I had several forms that used
help-inline. That’s now gone!
Overall I think that Bootstrap 3 is a move in the right direction for the framework. I do think that it will be a painful transition for many, however. My site is extremely simple on the public side, and it still took quite a while to make the move. More complex sites have a non-negligible migration path in front of them. Like the move from Bootstrap 1 to Bootstrap 2, you need to be prepared for some pain!