Most people who use bootstrap3 use the JavaScript also.
I suspect the worry is in 2 years (or however long they are bug fixing bootstrap3), newer browsers will start to break on bootstrap3, and you will have a complex way forward.
What bootstrap4 is doing is good, but it also can cause pain for users of bootstrap3.
Is that a common thing for browsers to break on older, previously compatible CSS?
* I see a list of themes priced at 100$ :/ (maybe that's a good thing?)
* "Moved from Less to Sass". OK, that's a late addition but always welcomed. (Although there was already an unofficial sass version of bootstrap.)
* "Opt-in flexbox support is here". Why would flexbox not be opt-out?
* "giving you more opinionated resets like box-sizing: border-box". About fucking time.
I still do, but I can see why it's opt-in rather than opt out.
I can see the utility in this. It's like an app store for bootstrap themes. The alternative is scouring the web, suffering the choice anxiety, working out if everything is compatible, etc.
Thanks for mentioning BEM, do you use it with sass?
If you already have a working project on Bootstrap 3 why bother upgrading?
If they had to maintain backwards compatibility they wouldn't be able to make a lot of the improvements they make.
In addition, it allows us to simplify CSS some by moving away from Bootstrap's crufty float-based grid system into a flexbox system, which simplifies some of our code.
The Bootstrap 3 to 4 upgrade isn't too bad as far as upgrades go.
Hope this can be released soon, I honestly feel tired waiting for Angular2 and Bootstrap4 and I began to use something else instead(vuejs that is, stuck with Bootstrap3)
https://css-tricks.com/snippets/css/a-guide-to-flexbox/
Reminds me of swing and similar layout managers.
Isn't about time we had a grid container that fixed this?
More interesting: the Galaxy S7 has a 2560x1440 display. Same for the HTC 10 and the LG V10. The iPhone 6 Plus has a 1920×1080 display, with the iPhone 7 about to be revealed.
I think its best not to use this in any projects until its out of beta.