This PR was merged into the repository by commit 3171d01.

The changes were merged into the following branches: main, 20.1.x

just out of curiosity: why is JIT still supported in angular?
AOT has been the default since angular 9 and provides many advantages.
Wouldn't it simplify angular if AOT was the only option? (of course with the disadvantage of making another breaking change)
Do many projects (beside testing) still use JIT?

@aceArt-GmbH my two cents:

My friends and I discuss this often, and we've concluded that the JIT compiler has become an obstacle to improving the Developer Experience (DX).

JIT creates "friction" when implementing desirable new features in the framework (as was the case with the global flag for standalone components). Furthermore, modern features like @defer don't function correctly with JIT, and future ideas such as "selectorless components" also wouldn't be feasible without adding more complexity and transformations.

We can get, much better solutions that don't involve sending the entire Angular compiler to the user's browser, which would significantly improve performance.

However, on the other hand, many existing applications rely on it.

Therefore, discontinuing it isn't so simple. First, a comprehensive list of all current JIT use cases needs to be created and understood. The ultimate goal is to develop viable and superior replacements for these use cases before removing it entirely.