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docs(LifecycleHooks): correct ngDoCheck description (#8807) 

The current behavior is for ngDoCheck to supplement, not override, the default change detector. OnChanges will still be called when DoCheck is implemented (fixes #7307).
This commit is contained in:
Zach Bjornson 2016-05-26 10:27:42 -07:00 committed by Miško Hevery
parent fa2ce8100b
commit 3a62023260
1 changed files with 8 additions and 11 deletions
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19
modules/@angular/core/src/metadata/lifecycle_hooks.ts
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@ -130,22 +130,19 @@ export abstract class OnChanges { abstract ngOnChanges(changes: SimpleChanges);
export abstract class OnInit { abstract ngOnInit(); } export abstract class OnInit { abstract ngOnInit(); }
/** /**
* Implement this interface to override the default change detection algorithm for your directive. * Implement this interface to supplement the default change detection algorithm in your directive.
* *
* `ngDoCheck` gets called to check the changes in the directives instead of the default algorithm. * `ngDoCheck` gets called to check the changes in the directives in addition to the default algorithm.
* *
* The default change detection algorithm looks for differences by comparing bound-property values * The default change detection algorithm looks for differences by comparing bound-property values
* by reference across change detection runs. When `DoCheck` is implemented, the default algorithm * by reference across change detection runs.
* is disabled and `ngDoCheck` is responsible for checking for changes.
* *
* Implementing this interface allows improving performance by using insights about the component, * Note that a directive typically should not use both `DoCheck` and {@link OnChanges} to respond to
* its implementation and data types of its properties. * changes on the same input. `ngOnChanges` will continue to be called when the default change detector
* detects changes, so it is usually unnecessary to respond to changes on the same input in both hooks.
* Reaction to the changes have to be handled from within the `ngDoCheck` callback.
* *
* Note that a directive should not implement both `DoCheck` and {@link OnChanges} at the same time. * You can use {@link KeyValueDiffers} and {@link IterableDiffers} to help add your custom check mechanisms.
* `ngOnChanges` would not be called when a directive implements `DoCheck`. Reaction to the changes
* have to be handled from within the `ngDoCheck` callback.
*
* Use {@link KeyValueDiffers} and {@link IterableDiffers} to add your custom check mechanisms.
* *
* ### Example ([live demo](http://plnkr.co/edit/QpnIlF0CR2i5bcYbHEUJ?p=preview)) * ### Example ([live demo](http://plnkr.co/edit/QpnIlF0CR2i5bcYbHEUJ?p=preview))
* *