Is it possible to install Vue 3, but still do things the "Vue 2" way? In other words, I see that Vue 3 has the new Composition API, but is that optional or the required way of doing things in Vue 3?
For some reason, I was thinking that Vue 3 still allowed you to do things the Vue-2 way, using the Options API instead. Is that not the case? Thanks.
Vue 3 does not require using the Composition API. The Options API is still available and will not be removed, as explained by two Vue core team members:
Thorsten Lünborg in Vue 3: Data down, Events up (19-MAY-2020):
IMPORTANT: The composition API is additive, it’s a new feature, but it doesn’t and will not replace the good ole “Options API” you know and love from Vue 1 and 2. Just consider this new API as another tool in your toolbox that may come in handy in certain situations that feel a little clumsy to solve with the Options API.
Ben Hong in Enjoy the Vue #48: "New in Vue 3: The Composition API" (19-JAN-2021):
[00:01:03]T: Yeah. Well, the first thing I remember hearing was that it was replacing the options API.
[00:01:08]BH: Big disclaimer. That isn’t happening. Big disclaimer.
...
[00:09:10]BH: [...] this is not something you need to go and rewrite your app in. [...] the composition API is not like, drop the options do composition. It's an additive thing that when you have a problem that it can solve, it's really great for that.
An early RFC for the Composition API had only considered deprecating the Options API:
A previous draft of this RFC indicated that there is the possibility of deprecating a number of 2.x options in a future major release, which has been redacted based on user feedback.
The Vue docs also confirm this:
Will Options API be deprecated?
No, we do not have any plan to do so. Options API is an integral part of Vue and the reason many developers love it. We also realize that many of the benefits of Composition API only manifest in larger-scale projects, and Options API remains a solid choice for many low-to-medium-complexity scenarios.