Is it necessary to set the property to null after calling ViewContainerRef.clear() when creating a component using ViewContainerRef and assigning an instance of it to the parent component responsible for child component creation in order to free up memory?
A common misconception is that assigning a parent component property to componentRef in Angular will automatically remove the component from memory.
In reality, Angular only destroys the component and removes its internal references to it. However, the reference to componentRef will still persist in your component property. To ensure proper memory cleanup, it's advisable to assign null to it. This way, the garbage collector can effectively clear memory.
Visual Example (add => clear => check)
@Component({
selector: 'my-app',
template: `
<div>
<button (click)="addComponent()">Add component</button>
<div #container></div>
<button (click)="clear()">Clear</button>
<button (click)="check()">Check</button>
</div>
`,
})
export class App {
comp: ComponentRef<DynamicComponent>;
constructor(
private vcRef: ViewContainerRef,
private resolver: ComponentFactoryResolver) {}
addComponent() {
let factory = this.resolver.resolveComponentFactory(DynamicComponent);
this.comp = this.vcRef.createComponent(factory);
}
clear() {
this.vcRef.clear();
}
check() {
alert(this.comp);
}
}
For more information, refer to:
It seems that Angular triggers the ngOnDestroy() method of dynamically created components when their parent component is removed by the Router.
If you'd like to see a live example, check out this Plunker: https://plnkr.co/edit/rAX6745xZi6EvP8N78IL?p=preview
import {Component, NgModule,Injector, ComponentFactoryResolver,
TemplateRef, ViewChild, ViewContainerRef} from '@angular/core'
import {BrowserModule} from '@angular/platform-browser'
import {Routes, RouterModule, Route} from '@angular/router';
@Component({
selector: 'my-other',
template: `<div>other</div>`
})
export class Other {}
// More code snippets and component definitions...
@NgModule({
imports: [ BrowserModule, RouterModule.forRoot(routes ],
declarations: [ App, MyComp, Parent, Other ],
entryComponents: [MyComp],
bootstrap: [ App ]
})
export class AppModule {}
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