ng model and change code example
Example 1: angular model change
<input type="checkbox" (ngModelChange)="myModel=$event" [ngModel]="mymodel">
Example 2: ngmodel change
<select [ngModel]="selectedItem" (ngModelChange)="onChange($event)">
onChange(newValue) {
console.log(newValue);
this.selectedItem = newValue; // don't forget to update the model here
// ... do other stuff here ...
}