downgradeModulelink
A helper function for creating an AngularJS module that can bootstrap an Angular module "on-demand" (possibly lazily) when a downgraded component needs to be instantiated.
参数
moduleFactoryOrBootstrapFn | Type: |
返回值
string
说明
Part of the upgrade/static library for hybrid upgrade apps that support AoT compilation.
It allows loading/bootstrapping the Angular part of a hybrid application lazily and not having to pay the cost up-front. For example, you can have an AngularJS application that uses Angular for specific routes and only instantiate the Angular modules if/when the user visits one of these routes.
The Angular module will be bootstrapped once (when requested for the first time) and the same reference will be used from that point onwards.
downgradeModule()
requires either an NgModuleFactory
or a function:
NgModuleFactory
: If you pass anNgModuleFactory
, it will be used to instantiate a module usingplatformBrowser
's bootstrapModuleFactory().Function
: If you pass a function, it is expected to return a promise resolving to anNgModuleRef
. The function is called with an array of extra Providers that are expected to be available from the returnedNgModuleRef
'sInjector
.
downgradeModule()
returns the name of the created AngularJS wrapper module. You can use it to declare a dependency in your main AngularJS module.
For more details on how to use downgradeModule()
see Upgrading for Performance.
使用说明
Apart from UpgradeModule
, you can use the rest of the upgrade/static
helpers as usual to build a hybrid application. Note that the Angular pieces (e.g. downgraded services) will not be available until the downgraded module has been bootstrapped, i.e. by instantiating a downgraded component.
You cannot use downgradeModule()
and UpgradeModule
in the same hybrid application.
Use one or the other.
Differences with UpgradeModule
Besides their different API, there are two important internal differences between downgradeModule()
and UpgradeModule
that affect the behavior of hybrid applications:
- Unlike
UpgradeModule
,downgradeModule()
does not bootstrap the main AngularJS module inside the Angular zone. - Unlike
UpgradeModule
,downgradeModule()
does not automatically run a $digest() when changes are detected in the Angular part of the application.
What this means is that applications using UpgradeModule
will run change detection more frequently in order to ensure that both frameworks are properly notified about possible changes. This will inevitably result in more change detection runs than necessary.
downgradeModule()
, on the other side, does not try to tie the two change detection systems as tightly, restricting the explicit change detection runs only to cases where it knows it is necessary (e.g. when the inputs of a downgraded component change). This improves performance, especially in change-detection-heavy applications, but leaves it up to the developer to manually notify each framework as needed.
For a more detailed discussion of the differences and their implications, see Upgrading for Performance.
You can manually trigger a change detection run in AngularJS using scope.$apply(...) or $rootScope.$digest().
You can manually trigger a change detection run in Angular using ngZone.run(...).