Angular 2 Set focus on first field of form on component load

Question

In my app I want to automatically set focus on first field of form on component load. Can anyone please guide how to achieve this without any repetition as I want this on every form (Reactive Forms) in my app.

Answer 1

你可以通过简单地将“autofocus”属性添加到你的输入元素来实现这一点。

<input class="form-control" [formControl]="name" autofocus>

Answer 2

You should use an directive to achieve this behavior.

This will show you the way how to do it: https://plnkr.co/edit/ttxCP7vCLkLtNb3Xiaah?p=preview

import {Component, NgModule, Directive, ElementRef, Renderer} from '@angular/core'
import {BrowserModule} from '@angular/platform-browser'

@Directive({
  selector: 'form[anyNameHere]'
})
export class SelectFirstInputDirective {

  constructor(private _eRef: ElementRef, private _renderer : Renderer) { }

  private _getInputElement(nativeElement: any): any {
    if (!nativeElement || !nativeElement.children) return undefined;
    if (!nativeElement.children.length && nativeElement.localName === 'input' && !nativeElement.hidden) return nativeElement;

    let input;

    [].slice.call(nativeElement.children).every(c => {
      input = this._getInputElement(c);
      if (input) return false; // break
      return true; // continue!
    });

    return input;
  }

  ngAfterViewInit() {
    let formChildren = [].slice.call(this._eRef.nativeElement.children);

    formChildren.every(child => {
      let input = this._getInputElement(child);

      if (input) {
        this._renderer.invokeElementMethod(input, 'focus', []);
        return false; // break!
      }

      return true; // continue!
    });
  }
}

@Component({
  selector: 'my-app',
  template: `
    <div>
      <h2>Hello {{name}}</h2>
      <form anyNameHere>
        <div class="form-group">
            <input hidden formcontrolname="firstName" type="text" class="form-control input-sm ng-pristine ng-valid ng-touched" placeholder="First Name" id="firstName">
            <label class="col-sm-3 control-label" for="firstName">Name</label>
            <div class="col-sm-9 form-inline">
              <div class="form-group">
                <div class="col-sm-12">
                  <input formcontrolname="firstName" type="text" class="form-control input-sm ng-pristine ng-valid ng-touched" placeholder="First Name" id="firstName">
                </div>
              </div>

              <div class="form-group">
                <div class="col-sm-12">
                  <input formcontrolname="lastName" type="text" class="form-control input-sm ng-untouched ng-pristine ng-valid" placeholder="Last Name" id="lastName">
                </div>
              </div>
            </div>
        </div>
      </form>
    </div>
  `,
})
export class App {
  constructor() {
    this.name = 'Angular2'
  }
}

@NgModule({
  imports: [ BrowserModule ],
  declarations: [ App, SelectFirstInputDirective ],
  bootstrap: [ App ]
})
export class AppModule {}

Answer 3

With Angular 4，Renderer has been deprecated, so the directive way is gone. But anyhow you can always use a "quick and dirty" way: add the reference to the element you want to set focus on and just use <reference-name>.focus()

<form [formGroup]="form" (ngSubmit)="onSubmit(form, $event); needFocus.focus()">
  <input placeholder="" formControlName="name" #needFocus>
</form>

Answer 4

HTML 自动聚焦属性就是这样做的

<input type="text" name="fname" autofocus>

Answer 5

Following approaches you can use => 1. You can do this by autoFoucs directive OR 2. Provide reference to your control like

 <input hidden #firstName formcontrolname="firstName" type="text" class="form-control input-sm ng-pristine ng-valid ng-touched" placeholder="First Name" id="firstName">

Then in ts file declare like this

export class App implements OnInit{
 @ViewChild('firstName') firstNameTextbox;
  constructor() {    
  }
ngOnInit() {
this.firstNameTextbox.nativeElement.focus();
}
}

Answer 6

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

@Directive({
  selector: 'form[appFocusFirstInput]'
})
export class FocusFirstInputDirective implements AfterViewInit {

  constructor(
    private element: ElementRef
  ) {
  }

  ngAfterViewInit(): void {
    const input = this.element.nativeElement.querySelector('input');
    if (input) {
      input.focus();
    }
  }
}