The proposed ES dynamic import() is now supported by the Angular CLI and the
larger toolchain. This renders the `loadChildren: string` API largely
redundant, as import() is far more natural, is less error-prone, and is
standards compliant. This commit deprecates the `string` form of
`loadChildren` in favor of dynamic import().
DEPRECATION:
When defining lazy-loaded route, Angular previously offered two options for
configuring the module to be loaded, both via the `loadChildren` parameter
of the route. Most Angular developers are familiar withthe `string` form of
this API. For example, the following route definition configures Angular to
load a `LazyModule` NgModule from `lazy-route/lazy.module.ts`:
```
[{
path: 'lazy',
loadChildren: 'lazy-route/lazy.module#LazyModule',
}]
```
This "magic string" configuration was previously necessary as there was
no dynamic module loading standard on the web. This has changed with the
pending standardization of dynamic `import()` expressions, which are now
supported in the Angular CLI and in web tooling in general. `import()`
offers a more natural and robust solution to dynamic module loading. The
above example can be rewritten to use dynamic `import()`:
```
[{
path: 'lazy',
loadChildren: () => import('./lazy-route/lazy.module').then(mod => mod.LazyModule),
}]
```
This form of lazy loading offers significant advantages in terms of:
* type checking via TypeScript
* simplicity of generated code
* future potential to run natively in supporting browsers
(see: [caniuse: dynamic import()](https://caniuse.com/#feat=es6-module-dynamic-import))
As a result, Angular is deprecating the `loadChildren: string` syntax in
favor of ES dynamic `import()`. An automatic migration will run during
`ng upgrade` to convert your existing Angular code to the new syntax.
PR Close#30073
The router loadChildren property already supports a promise that returns a NgModuleFactory, but the typings cause the compilation to fail.
PR Close#29392
This option means guards and resolvers will ignore changes when a provided predicate function returns `false`. This supports use cases where an application needs to ignore some param updates but not others. For example, changing a sort param in the URL might need to be ignored, whereas changing the a `project` param might require re-run of guards and resolvers.
Related to #26861#18253#27464
PR Close#27682
This option means guards and resolvers will ignore changes to matrix parameters. Guards and resolvers will be rerun when the path changes, when path parameters change, or when query parameters change.
The primary use case for such a mode is when updating the UI and getting the URL to be in sync with local changes. For example, if displaying a sortable table, changing the sort direction is often handled by the table itself. But you would want to update the URL to be in sync with what's being displayed to the user. As long as the table sort direction is stored as a matrix parameter, you can use this option to update the URL without causing the overhead of re-running guards and resolvers.
Related to #26861#18253
PR Close#27464
This option means guards and resolvers will ignore changes to optional
parameters such as query and matrix params. When the path or any path
params change, guards and resolvers will be run
Related to discussion in #18253
FW-560 #resolve
PR Close#26861
Judy Bogart
Alex Rickabaugh
Filipe Silva
Jason Aden
Pete Bacon Darwin
George Wilde
Igor Minar
Rafael
Aaron Hoffman
Igor Minar
Victor Berchet
Dzmitry Shylovich