What is the difference between ngOnInit and constructor in Angular?

Short answer: Aspect Constructor ngOnInit Purpose Initializes the class Lifecycle hook, called after constructor Use Case Inject dependencies Fetch data, initialize logic Called By JavaScript engine Angular

Example code

constructor(private userService: UserService) {} ngOnInit() { this.userService.getUsers().subscribe(users => this.users = users); } Real-Time Example: In a profile component: Use constructor to inject ProfileService Use ngOnInit to fetch the user's data after initialization

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1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.