Angular 2+: Get child element of @ViewChild()

问题:

How can I access the child elements (here: <img>) of @ViewChild() in Angular 2+ without explicit declaration?

In template.html

<div #parent>
  <!-- There can be anything than <img> -->
  <img src="http://localhost/123.jpg" alt="">
</div>

In component.ts

@ViewChild('parent') parent;

public getFirstChild() {
   this.firstChild = this.parent.? //
}

The aim is, to be able to create a universal component that uses:

<div #parent>
    <ng-content></ng-content>
</div>

So the child elements of #parent need to be accessible without explicit declaration.

回答1:

You can use the nativeElement property of the ElementRef given by ViewChild to get the corresponding HTML element. From there, standard DOM methods and properties give access to its children:

• element.children
• element.querySelector
• element.querySelectorAll
• etc.

For example:

@ViewChild("parent") private parentRef: ElementRef<HTMLElement>;

public getChildren() {
  const parentElement = this.parentRef.nativeElement;
  const firstChild = parentElement.children[0];
  const firstImage = parentElement.querySelector("img");
  ...
}

See this stackblitz for a demo.

回答2:

use ViewChildren instead which gets all elements with same tag.

@ViewChildren('parent') parents: QueryList<any>;

To convert those elements to array:

const arr = this.parent.toArray();

Choose first element:

const el = arr[0]

Access child html of first element: const innerHtml = el.nativeElement.innerHtml;

回答3:

In your case, when you need only one and first child.

this.parent.nativeElement.firstChild