accordion.component.ts

import { Component } from '@angular/core';
import { NgbPanelChangeEvent } from '@ng-bootstrap/ng-bootstrap';

@Component({
    selector: 'app-ngbd-accordion-basic',
    templateUrl: 'accordion.component.html'
})
export class NgbdAccordionBasicComponent {
    disabled = false;

    beforeChange($event: NgbPanelChangeEvent) {
        if ($event.panelId === 'preventchange-2') {
            $event.preventDefault();
        }

        if ($event.panelId === 'preventchange-3' && $event.nextState === false) {
            $event.preventDefault();
        }
    }
}