NG Interview Set I - Lifecycle Hooks Questions

Question 1

What is the possible order of lifecycle hooks in Angular?

Answer 1

• ngOnChanges, ngOnInit, ngDoCheck, ngAfterContentInit, ngAfterContentChecked, ngAfterViewInit, ngAfterViewChecked, ngOnDestroy

Question 2

When will ngOnInit be called?

Answer 2

• Called once, after the first ngOnChanges

Question 3

How would you make use of onNgInit()?

Answer 3

• Fetch initial component data (e.g. from server)

Question 4

What would you consider a thing you should be careful doing on onNgInit()?

Answer 4

• You cannot expect the component’s children’s data-bound properties to have been checked at this point

Question 5

What is the difference between onNgInit() and constructor() of a component?

Answer 5

• A directive’s data-bound input properties are not set until after construction, so that’s one difference