formcontrol subscribe valuechanges code example
Example 1: angular formgroup on value change
this.reactiveForm.get("firstname").valueChanges.subscribe(x => {
console.log('firstname value changed')
console.log(x)
})
Example 2: angular 9 form value changes
this.reactiveForm.get("firstname").valueChanges.subscribe(selectedValue => {
console.log('firstname value changed')
console.log(selectedValue) //latest value of firstname
console.log(this.reactiveForm.get("firstname").value) //latest value of firstname
})