sidenav-angular/src/app/sidenav/sidenav-drawer-item/sidenav-drawer-item.compone...

import { Component, OnInit, Input, ViewChild } from '@angular/core';
import { SidenavService } from '../sidenav.service';
import { startWith, map } from "rxjs/operators";

@Component({
  selector: 'sidenav-drawer-item',
  templateUrl: './sidenav-drawer-item.component.html',
  styleUrls: ['./sidenav-drawer-item.component.css']
})
export class SidenavDrawerItemComponent implements OnInit {
  @Input('route') route;
	@Input('itemTitle') title;
	@Input('check') check?;

	@ViewChild('button', { static: true }) element;

	constructor(
		public _menu: SidenavService 
	){ }
	
	ngOnInit(){
		if(this.check)
			this._menu.currentRouteChange.pipe(
				startWith(this._menu.currentRoute),
				map(url => url)
			).subscribe((url) => {
				const _regex = new RegExp(this.check)
				if(_regex.exec(url)) this._menu.setSelectedItem(this.element.nativeElement)
			})
	}
}