References
Oleksa Novyk | GitHub

@ViewChild

This is the documentation for Angular 6.
You can switch to the latest version Angular 9.

Property decorator that configures a view query. The change detector looks for the first element or the directive matching the selector in the view DOM. If the view DOM changes, and a new child matches the selector, the property is updated.

View queries are set before the ngAfterViewInit callback is called.

Example

import {AfterViewInit, Component, Directive, ViewChild} from '@angular/core';

@Directive({selector: 'child-directive'})
class ChildDirective {
}

@Component({selector: 'someCmp', templateUrl: 'someCmp.html'})
class SomeCmp implements AfterViewInit {
  @ViewChild(ChildDirective) child: ChildDirective;

  ngAfterViewInit() {
    // child is set
  }
}

Options

@ViewChild(
  selector: Type<any>|Function|string, 
  opts?: {read?: any},
)

selector#

selector: Type<any>|Function|string

The directive type or the name used for querying.

Supported selectors include:

  • any class with the @Component or @Directive decorator
  • a template reference variable as a string (e.g. query <my-component #cmp></my-component> with @ViewChild('cmp'))
  • any provider defined in the child component tree of the current component (e.g. @ViewChild(SomeService) someService: SomeService)
  • any provider defined through a string token (e.g. @ViewChild('someToken') someTokenVal: any)
  • a TemplateRef (e.g. query <ng-template></ng-template> with @ViewChild(TemplateRef) template;)

opts#

opts?: {read?: any}

Additional options.

  • read - read a different token from the queried elements.