Angular - if statement to checking current route

I want to check if user he is coming from page 1 or page 2 using current url route , then pass parameters depending on page url . I used if statement and ngif to checking the current url route . But problem is the if statement doesn't work properly .

code :

    page1:boolean= false
   page2:boolean= false

  constructor(private router:Router) { 


     if (this.router.url === '/tabs/tab1') {
            this.page1= true
            this.page2= false
            this.getData()

        } else if (this.router.url === '/tabs/tab2'){
          this.page1= false 
          this.page2= true

          this.getData()

        }
}

html

  <ng-container *ngIf="page1; else elseTemplate">
   // check if page 1 route /tabs/tab1' display data page1 and hide data 
      page 2
  // for page 1 different data   
  </ng-container>
  <ng-template #elseTemplate>

  </ng-template>

  <ng-container *ngIf="page2; else elseTemplate">
   // check if page2 route /tabs/tab2' display data page 2 and hide 
       data page 1

    // Also of paga 2 different data 
  </ng-container>
  <ng-template #elseTemplate>

  </ng-template>