The Webpack 5 automatic public path support can cause an incorrect public path to be used to load assets and lazy loaded routes. The current logic relies on the last script element found at runtime in the application's index HTML which may not be related to the application scripts. Now if a `deployUrl` is not specified, the Webpack `publicPath` option is defaulted to an empty string which provides equivalent behavior to Webpack 4.
In Webpack 5, the Webpack callback must be used when Webpack is running in watch mode.
Related warning
```
.(node:6565) [DEP_WEBPACK_WATCH_WITHOUT_CALLBACK] DeprecationWarning: A 'callback' argument need to be provided to the 'webpack(options, callback)' function when the 'watch' option is set. There is no way to handle the 'watch' option without a callback.
```
Webpack 5 now uses a `chunkHash` hook that is accessible from `JavascriptModulesPlugin.getCompilationHooks()`. The `hashForChunk` hooks have been deprecated in Webpack 5.
TypeScript files had the potential to be processed twice by the build optimizer. This did not affect the output code but could lead to longer production build times. The build optimizer is now configured in one centralized location for both TypeScript and JavaScript files. The Webpack configuration partial for TypeScript support is also reduced to one common function for both AOT and JIT as a result.
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.
The programmatic APIs for the builders are now explicitly marked as experimental. This allows the package to use a stable versioning scheme while also continuing to provide access to the experimental programmatic API elements of the package.
With the minimum version of Node.js now set to v12, the promise fs API can now be leveraged within the tooling.
This change also uses `copyFile` (with copy-on-write where available) to setup the the service worker files as well a streaming APIs to generate service worker hashes. Both of which improves performance and reduces memory usage.
A new build option named `inlineStyleLanguage` has been introduced that will allow a project to define the stylesheet language used in an application's inline component styles. Inline component styles are styles defined via the `styles` property within the Angular `Component` decorator. Both JIT and AOT mode are supported. However, JIT mode requires that inline styles only be string literals (compile-time partial evaluation is not supported in JIT mode). Currently supported language options are: `CSS` (default), `Sass`, `SCSS`, and `Less`. If the option is not specified, `CSS` will be used and enables existing projects to continue to function as expected.
In some scenarios in Webpack 5 percentage goes from 1 back to 0.99, ex: 0.99 -> 1 -> 0.99 -> 1. This causes the "complete" message to be displayed multiple times.
The internal Webpack configuration now includes support for style rules with MIME type conditions. This allows the data URIs generated for inline component CSS styles by the Angular Webpack plugin to be processed with the same loaders as file based styles.
With this change we configure new libraries to be published using Ivy partial compilation instead of the deprecated View Engine rendering engine, we also remove several view engine specific `angularCompilerOptions`.
New libraries can be published using this format, as they are not depend upon by View Engine libraries or application.
With this change Webpack 5 is now used by the Angular tooling to build applications. Webpack 4 usage and support has been removed.
No project level configuration changes are required to take advantage of the upgraded Webpack version when using the official Angular builders.
Custom builders based on this package that use the experimental programmatic APIs may need to be updated to become compatible with Webpack 5.
BREAKING CHANGE: Webpack 5 lazy loaded file name changes
Webpack 5 generates similar but differently named files for lazy loaded JavaScript files in development configurations (when the `namedChunks` option is enabled).
For the majority of users this change should have no effect on the application and/or build process. Production builds should also not be affected as the `namedChunks` option is disabled by default in production configurations.
However, if a project's post-build process makes assumptions as to the file names then adjustments may need to be made to account for the new naming paradigm.
Such post-build processes could include custom file transformations after the build, integration into service-side frameworks, or deployment procedures.
Example development file name change: `lazy-lazy-module.js` --> `src_app_lazy_lazy_module_ts.js`
BREAKING CHANGE: Webpack 5 web worker support
Webpack 5 now includes web worker support. However, the structure of the URL within the `Worker` constructor must be in a specific format that differs from the current requirement.
Web worker usage should be updated as shown below (where `./app.worker` should be replaced with the actual worker name):
Before: `new Worker('./app.worker', ...)`
After: `new Worker(new URL('./app.worker', import.meta.url), ...)`
With recent improvements to the dev-server builder unit tests, additional parallel testing should now be possible.
The unused `express` dependencies are also removed.
This change updates the remainder of the non-builder harness tests to use a random port when testing. This change reduces the frequency of test flakes as well as improves the opportunity for parallel test execution.
With the removal of the deprecated ViewEngine-based Webpack plugin, the ivy namespace export that was previously used is now deprecated in favor of direct exports of the Ivy-based plugin.
The default Jasmine test timeout is set to 2.5 minutes for all builder tests. The smaller timeouts (that are now removed from individual tests) can lead to test flakes especially on CI which can have large performance variability.
