import { Component , OnInit } from '@angular/core' ; @ Component ( { selector : 'expansion-panel' , templateUrl : './expansion-panel.component.html' , styleUrls : [ './expansion-panel.component.scss' ] } ) export class ExpansionPanelComponent implements OnInit { panelOpenState = false ; step = 0 ; constructor ( ) { } ngOnInit ( ) { } setStep ( index ) { this . step = index ; } nextStep ( ) { this . step ++ ; } prevStep ( ) { this . step -- ; } }