[mosdl]

You still have to debug those - if you set the wrong state/etc, things will break like before.

All react does is remove the need to modify the DOM directly when you want to modify things.

[richthegeek]

But setting the wrong state is someting that happens far less and is much more traceable, because the encapsulation of state changes into a single place massively reduces the side effects (and global state) that were the cause of 90% of those bugs in the bad old days.

[mosdl]

The OP said: "The bugs of yesteryear, tracking down which procedural code path led to modifying a variable, are mostly gone with React."

Which is wrong, React doesn't address that in any way, shape or form.