How to use FormControl statusChanges in angular2?

Question

i am new to angular2 and i want to trigger a function when the user selects some value in a dropDown. So i tried to implement statusChange of the FormControl class but it is not getting triggered,

wonder how and when to use the statusChange in angular2 this is my code

class policy{
 subCategory: FormControl = new FormControl();
 ngOnInit() {
            this.subCategory.statusChanges.subscribe(
                s => {
                    alert('success');
                }, e => {
                    alert('error');
                }, () => {
                    alert('complete');
                }
            );
        }
}

I thought by implementing statusChanges i can trigger the success function on every change of value on the dropdown, obviously it is now working.

UPDATE 1

I have updated the plunkr

Answer 1

As the comments stated, you probably wanted valueChanges instead. However, for the thousands of other folks who arrived here from searching for how statusChanges works, here you go:

this.subCategory.statusChanges.subscribe( (status) => {
  console.log(status); //status will be "VALID", "INVALID", "PENDING" or "DISABLED"
})

The docs describe those 4 possible values as follows:

• VALID: This control has passed all validation checks.
• INVALID: This control has failed at least one validation check.
• PENDING: This control is in the midst of conducting a validation check.
• DISABLED:This control is exempt from validation checks. These status values are mutually exclusive, so a control cannot be both valid AND invalid or invalid AND disabled.