How to use onBlur event on Angular2?

Use (eventName) for while binding event to DOM, basically () is used for event binding. Also use ngModel to get two way binding for myModel variable.

Markup

<input type="text" [(ngModel)]="myModel" (blur)="onBlurMethod()">

Code

export class AppComponent { 
  myModel: any;
  constructor(){
    this.myModel = '123';
  }
  onBlurMethod(){
   alert(this.myModel) 
  }
}

Demo

Alternative(not preferable)

<input type="text" #input (blur)="onBlurMethod($event.target.value)">

Demo

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For model driven form to fire validation on blur, you could pass updateOn parameter.

ctrl = new FormControl('', {
   updateOn: 'blur', //default will be change
   validators: [Validators.required]
}); 

Design Docs