[Breaking change] babel-loader => ts-loader in web build builder 8.5.0

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Expected Behavior

Being able to use all Typescript features.

Current Behavior

babel-loader doesn’t support all Typescript features, e.g., const enum, like ts-loader does.

Failure Information (for bugs)

ERROR in /path/to/file.ts
Module build failed (from /path/to/repo/node_modules/babel-loader/lib/index.js):
SyntaxError: /path/to/file.ts: 'const' enums are not supported.

See also https://github.com/babel/babel/issues/8741.

Steps to Reproduce

Just run a web project build that includes const enums.

Context

Please provide any relevant information about your setup:

Version of Nx used: 8.5.0

Relevant commit: https://github.com/nrwl/nx/commit/811c50b Relevant PR: https://github.com/nrwl/nx/pull/1792

Other

The below are other potential breaking changes that are related only in that they were done in the same commit/PR. Happy to move these into separate issues if preferable. In no particular order:

• Filename output was changed (https://github.com/nrwl/nx/commit/811c50b#diff-385b9a18cb3b6256450dc76ddcc286a1R22-R28)
• Differential loading option was removed completely (i.e., would only be an issue those who weren’t using it)
• This is not a breaking change, but something I’d call out: the E2E tests that was checking for successful ES5 transpilation were changed/removed (https://github.com/nrwl/nx/commit/811c50b#diff-cea283cab47e0b2561dd9a84ee5ae998L131-R133 and https://github.com/nrwl/nx/commit/811c50b#diff-a83f7b1d90c9a62dd914ccc27968e4faL38-L41)

[jaysoo]

@atifsyedali Hey, thanks for chiming in. I don’t think it’ll quite work with using transpileOnly since depending on what babel-plugins you use, it may not transpile using just tsc. I think we should be able to get support parity with prevous ts-loader setup.

[atifsyedali]

Our codebase broke wrt namespaces, const enums, decorators, and more.

@jaysoo Can’t we have the Typescript compiler in transpileOnly mode pipe output to Babel, with the option of disabling Babel altogether? Then in parallel use the ForkTsChecker plugin.

This may seem like it may make the builds slower, but ‘@babel/preset-typescript’ is already installed in babel, which you can now remove if you first pipe through tsc before babel.