What is ChangeDetectionStrategy in Angular?

In Angular, the ChangeDetectionStrategy is an enumeration that determines when Angular updates the view with the latest changes in data. It’s used to control the change detection process for a component and its children.

There are two possible values for ChangeDetectionStrategy:

1. ChangeDetectionStrategy.Default (also known as “default” or “dynamic”) – This is the default change detection strategy in Angular. It means that Angular will run change detection on a component and its children every time there is an event, async operation or property binding update.
2. ChangeDetectionStrategy.OnPush – With this strategy, Angular will run change detection only when an input reference changes (for example, when a new object is passed to the input property) or when an event is triggered from within the component. This strategy can lead to better performance compared to the default strategy.

You can specify the change detection strategy for a component by using the changeDetection property in the @Component decorator, for example:

@Component({
  selector: 'app-my-component',
  template: '...',
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class MyComponent { ... }