<ion-input type="text" placeholder="Enter a Town, Province or City" name="newPlace" [(ngModel)]="newPlace" id="empty"></ion-input>

<button ion-button block type="submit" (click)="addLocation()">ADD AND SAVE MORE LOCATIONS</button>

addLocation(){
     if( document.getElementById('empty').value === '' ){
          alert('empty');
     }
  }

<button ion-button block type="button" (click)="addLocation()">ADD AND SAVE MORE LOCATIONS</button>

<button ion-button block type="button" (click)="addLocation(newPlace)">ADD AND SAVE MORE LOCATIONS</button>

addLocation(newPlace){
     if(newPlace === '' ){
          alert(newPlace);
     }
  }