modify ngModel based on value 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 ...
}