Prepares the `@angular-devkit/build-webpack` package for the eventual change of enabling the
TypeScript `useUnknownInCatchVariables` option. This option provides additional
code safety by ensuring that the catch clause variable is the proper type before
attempting to access its properties. Similar changes will be needed in the other
packages in the repository prior to enabling `useUnknownInCatchVariables`.
Since Angular 8, the CLI has transformed decorator metadata to a form that can be used by the Angular dependency injector without the TDZ limitations of Typescript's decorator metadata emit feature.
As a result, a JIT application compiled with the CLI no longer requires the reflect metadata polyfill that was provided by `core-js`.
This polyfill was also the last remaining usage of the `core-js` package within `@angular-devkit/build-angular` which allows the `core-js` package to also be removed.
Refs: https://github.com/angular/angular-cli/pull/14473 & https://github.com/angular/angular/pull/37382
BREAKING CHANGE: Reflect metadata polyfill is no longer automatically provided in JIT mode
Reflect metadata support is not required by Angular in JIT applications compiled by the CLI.
Applications built in AOT mode did not and will continue to not provide the polyfill.
For the majority of applications, the reflect metadata polyfill removal should have no effect.
However, if an application uses JIT mode and also uses the previously polyfilled reflect metadata JavaScript APIs, the polyfill will need to be manually added to the application after updating.
To replicate the previous behavior, the `core-js` package should be manually installed and the `import 'core-js/proposals/reflect-metadata';` statement should be added to the application's `polyfills.ts` file.
With this change we update the TypeScript compilation target to `ES2020` for both new and existing projects. This is because all browsers that Angular supports (https://angular.io/guide/browser-support) support `ES2020` features without the need for polyfills.
rxjs 6 requires directory imports which are not support in ES modules. Disabling `fullySpecified` allows Webpack to ignore cases such as this until the package can be updated to use package exports.
Webpack-dev-server doesn't handle concurrency very well. When using port 0, and 2 processes start at the same time, they end up being given the same port. The main reason for the issue is that it find a free port, put only uses at a later stage.
BREAKING CHANGE:
Support for `webpack-dev-server` version 3 has been removed. For more information about the migration please see: https://github.com/webpack/webpack-dev-server/blob/master/migration-v4.md
Note: this change only affects users depending on `@angular-devkit/build-webpack` directly.
rules_nodejs 4 requires that a package_name property be specified within a ts_library rule for the output to be linked into the package repository. Failing to add the property can cause test failures due to unresolved packages.
