@Attribute decorator in Angular Js

import {

    Component,

    Attribute

} from '@angular/core';

export type ButtonType = 'primary' | 'secondary';

@Component({

    selector: 'app-button',

    template: `

    <button [ngClass]="type">

      <ng-content></ng-content>

    </button>

  `

})

export class ButtonComponent {

    constructor(@Attribute('type') public type: ButtonType = 'primary') {}

}

  @Attribute decorator in Angular 2 

 Angular will evaluate it once and forget about it. As a general rule, I prefer the @Attribute() approach when the string is a fixed value that never changes.

Use Example 

<app-button type="secondary" (click)="click()">Click</app-button>