Move away from Classic module resolution as default for all module kinds

TypeScript’s original module resolution strategy (the Classic resolution strategy) has some strange behavior that apparently doesn’t actually reflect any other resolution strategy. It seems strange that those using non-CommonJS emit targets get this behavior by default.

Classic resolution also causes many disk probes during the walk up the project root - assuming that this strategy does eventually succeed in most cases, it seems like most uses could be subsumed by:

• Using relative paths.
• Modifying the baseUrl and paths properties in tsconfig.json.

After discussing with @vladima, we think it is worth considering switching the default resolution strategy for all module targets to Node.

Here’s what needs to be done:

• Investigate existing tsconfig.jsons that target esXXXX` and have no explicit/implied resolution strategy.
• Determine the downstream effects to a change to defaults
• Determine if this change outweighs the potential breakage
• Implement if appropriate

[brhumphe]

I’m pretty new to typescript, and this unexpected behavior really tripped me up (see #11712 ). The vast majority of tutorials assume the user is developing with npm, including those on the official website, so the defaults should (from my noob-ish perspective) reflect that most common use case.

There are more than enough unexpected pitfalls in web development. Eliminating this one would be awesome.

[DanielRosenwasser]

Thanks for weighing in @kitsonk. We knew that Dojo was using classic in some capacity, but we figured that there shouldn’t be any major changes, and for new projects people shouldn’t be caught off guard by this behavior.

Additionally, we wouldn’t remove classic, we’d only switch the defaults for non-CommonJS resolutions, so users could still opt back in to classic.

@aluanhaddad, it’d also be good to get your thoughts here too.