How can I select an element in a component template?

Instead of injecting ElementRef and using querySelector or similar from there, a declarative way can be used instead to access elements in the view directly:

<input #myname>

@ViewChild('myname') input; 

element

ngAfterViewInit() {
  console.log(this.input.nativeElement.value);
}

StackBlitz example

• @ViewChild() supports directive or component type as parameter, or the name (string) of a template variable.
• @ViewChildren() also supports a list of names as comma separated list (currently no spaces allowed @ViewChildren('var1,var2,var3')).
• @ContentChild() and @ContentChildren() do the same but in the light DOM (<ng-content> projected elements).

descendants

@ContentChildren() is the only one that allows to also query for descendants

@ContentChildren(SomeTypeOrVarName, {descendants: true}) someField; 

{descendants: true} should be the default but is not in 2.0.0 final and it's considered a bug
This was fixed in 2.0.1

read

If there are a component and directives the read parameter allows to specify which instance should be returned.

For example ViewContainerRef that is required by dynamically created components instead of the default ElementRef

@ViewChild('myname', { read: ViewContainerRef }) target;

subscribe changes

Even though view children are only set when ngAfterViewInit() is called and content children are only set when ngAfterContentInit() is called, if you want to subscribe to changes of the query result, it should be done in ngOnInit()

https://github.com/angular/angular/issues/9689#issuecomment-229247134

@ViewChildren(SomeType) viewChildren;
@ContentChildren(SomeType) contentChildren;

ngOnInit() {
  this.viewChildren.changes.subscribe(changes => console.log(changes));
  this.contentChildren.changes.subscribe(changes => console.log(changes));
}

direct DOM access

can only query DOM elements, but not components or directive instances:

export class MyComponent {
  constructor(private elRef:ElementRef) {}
  ngAfterViewInit() {
    var div = this.elRef.nativeElement.querySelector('div');
    console.log(div);
  }

  // for transcluded content
  ngAfterContentInit() {
    var div = this.elRef.nativeElement.querySelector('div');
    console.log(div);
  }
}

get arbitrary projected content

See Access transcluded content

You can get a handle to the DOM element via ElementRef by injecting it into your component's constructor:

constructor(private myElement: ElementRef) { ... }

Docs: https://angular.io/docs/ts/latest/api/core/index/ElementRef-class.html

Angular 4+: Use renderer.selectRootElement with a CSS selector to access the element.

I've got a form that initially displays an email input. After the email is entered, the form will be expanded to allow them to continue adding information relating to their project. However, if they are not an existing client, the form will include an address section above the project information section.

As of now, the data entry portion has not been broken up into components, so the sections are managed with *ngIf directives. I need to set focus on the project notes field if they are an existing client, or the first name field if they are new.

I tried the solutions with no success. However, Update 3 in this answer gave me half of the eventual solution. The other half came from MatteoNY's response in this thread. The result is this:

import { NgZone, Renderer } from '@angular/core';

constructor(private ngZone: NgZone, private renderer: Renderer) {}

setFocus(selector: string): void {
    this.ngZone.runOutsideAngular(() => {
        setTimeout(() => {
            this.renderer.selectRootElement(selector).focus();
        }, 0);
    });
}

submitEmail(email: string): void {
    // Verify existence of customer
    ...
    if (this.newCustomer) {
        this.setFocus('#firstname');
    } else {
        this.setFocus('#description');
    }
}

Since the only thing I'm doing is setting the focus on an element, I don't need to concern myself with change detection, so I can actually run the call to renderer.selectRootElement outside of Angular. Because I need to give the new sections time to render, the element section is wrapped in a timeout to allow the rendering threads time to catch up before the element selection is attempted. Once all that is setup, I can simply call the element using basic CSS selectors.

I know this example dealt primarily with the focus event, but it's hard for me that this couldn't be used in other contexts.

UPDATE: Angular dropped support for Renderer in Angular 4 and removed it completely in Angular 9. This solution should not be impacted by the migration to Renderer2. Please refer to this link for additional information: Renderer migration to Renderer2

import { Component, ElementRef, OnInit } from '@angular/core';

@Component({
  selector:'display',
  template:`
   <input (input)="updateName($event.target.value)">
   <p> My name : {{ myName }}</p>
  `
})
class DisplayComponent implements OnInit {
  constructor(public element: ElementRef) {
    this.element.nativeElement // <- your direct element reference 
  }
  ngOnInit() {
    var el = this.element.nativeElement;
    console.log(el);
  }
  updateName(value) {
    // ...
  }
}

Example updated to work with the latest version

For more details on native element, here