To make our test output i.e. devmode output more aligned
with what we produce in the NPM packages, or to be more
aligned with what Angular applications will usually consume,
the devmode output is switched from ES5 to ES2015.
Additionally various tsconfigs (outside of Bazel) have been
updated to match with the other parts of the build. The rules
are:
ES2015 for test configurations, ES2020 for actual code that will
end up being shipped (this includes the IDE-only tsconfigs).
PR Close#44505
Enables the `esModuleInterop` for all TypeScript compilations in the
project. This allows us to emit proper ESM-compatible code. e.g.
consider the following import:
```ts
import * as ts from 'typescript';
```
This import currently will break at runtime in NodeJS because the
`typescript` package is not shipping ESM. It's still a CommonJS module.
ES modules are able to import from `typescript` though, using an import
statement as above, but everything in `module.exports` is being exposed
as the `default` named export. TypeScript at runtime does not have any
other named exports, so for actual ESM compatibility, all of our imports
need to be switched to:
```
import ts from 'typescript';
```
The `esModuleInterop` option allows this to work even though the
`d.ts` file of TS currently suggests that there are _only_ named exports.
The TypeScript language service will now suggest the correct import form as
shown above. It doesn't enforce that unfortunately, but this commit also
adds a lint rule that enforces certain patterns so that we emit imports
that are compatible with both ESM and CJS output (CJS still needed here
since tests run with CJS devmode output still; this is a future project
to switch that over to ESM!)
PR Close#43431
Paul Gschwendtner