how to programmatically set or reset checkbox

Purpose: when a particular checkbox is checked or unchecked, the program must change a number of other checkboxes according to programmed rules.

<input type="checkbox" id="chkbox" (change)="onChangeChk($event)">Test Checkbox

  onChangeChk($event) {
    $event.srcElement.value = "on"; // or "off"
  }

The checkbox remains in its original state no matter how the onChangeChk sets it.

Thanks for you help on this. :-)