Paul Gschwendtner 25eaaa24b5 fix(@angular-devkit/build-angular): downlevel class properties when targeting Safari <=v15
The Angular compiler is dependent on static fields being attached to
user-defined classes. e.g. `static ecmp = defineComponent`.

These static fields sometimes rely on variables from outside of the
class. e.g. the Angular compiler generates constants for content
projection that are then accessed in the static field initializer.

Surprisingly such access to these variables may break in Safari <=v15
when a page is loaded without devtools open. The bug (already solved in
v16 of Safari)- is very subtle, hard to re-reproduce but basically
variable scope tracking is broken. This bug is triggered by additional
parenthesis in the initializer expression. See:
https://bugs.webkit.org/show_bug.cgi?id=236843.

The TypeScript compiler may generate such additional parenthesis when
it tries to adjust the `this` context when invoking methods, such as for
defining animations in the `ecmp` definition.

More details can be found here:
https://github.com/angular/angular-cli/issues/24355#issuecomment-1333477033

To ensure Angular applications are not subject to this bug when
targeting Safari <=v15. v15 Safari, both for iOS and Mac is still part of
the default CLI browserslist with `last 2 Safari majors` (at time of
writing).

Note that it is important that the Babel plugin properly handles the
downleveling of static block-defined members. TypeScript will transform
static fields, like `static ecmp` into `static { this.ecmp = X }` when
`useDefineForClassFields = false` (which is the case for CLI apps). The
class properties plugin from Babel seems to handle this in an acceptable
way. Unlike actual static fields, Babel will not use helpers like
`defineProperty` for such extracted static blocks though. e.g.

See repro: https://gist.github.com/devversion/dec0dea26e348c509921bf62079b60be

```js
class Test {
  x = true;

  static b = true;
  static {
    this.a = true;
  }
}

// into

class X {
  constructor() {
    _defineProperty(this, "x", true);
  }
}
_defineProperty(X, "b", true);
X.a = true;
```

note that in practice TypeScript with `useDefineForClassFields = false`
will put non-static members into the constructor as normal assignments
regardless- so there would be no change by the Babel plugin.

Fixes #24355.
2022-12-02 09:05:29 +00:00
..
2022-11-21 11:07:16 -05:00

@angular-devkit/build-angular

This package contains Architect builders used to build and test Angular applications and libraries.

Builders

Name Description
app-shell Build an Angular App shell.
browser Build an Angular application targeting a browser environment.
dev-server A development server that provides live reloading.
extract-i18n Extract i18n messages from an Angular application.
karma Execute unit tests using Karma test runner.
ng-packagr Build and package an Angular library in Angular Package Format (APF) format using ng-packagr.
server Build an Angular application targeting a Node.js environment.
protractor Deprecated - Run end-to-end tests using Protractor framework.

Disclaimer

While the builders when executed via the Angular CLI and their associated options are considered stable, the programmatic APIs are not considered officially supported and are not subject to the breaking change guarantees of SemVer.