Why lifecycle hooks matter in Angular - Quick Recap

Recall & Review

beginner

What are lifecycle hooks in Angular?

Lifecycle hooks are special methods in Angular components that let you tap into key moments of a component's life, like when it is created, updated, or destroyed.

beginner

Why is ngOnInit important?

ngOnInit runs once after the component is created. It is used to initialize data or start processes like fetching data from a server.

intermediate

How do lifecycle hooks help with resource management?

Hooks like ngOnDestroy let you clean up resources such as timers or subscriptions to avoid memory leaks when a component is removed.

intermediate

What happens if you don’t use lifecycle hooks properly?

Without proper use of lifecycle hooks, your app might fetch data too late, leak memory, or behave unpredictably because components miss key setup or cleanup steps.

beginner

Name two lifecycle hooks and their main purpose.

ngOnInit: Initialize component data.<br>ngOnDestroy: Clean up before component is removed.

Which lifecycle hook is called once after component creation?

A ngDoCheck

B ngOnDestroy

C ngAfterViewInit

D ngOnInit

ngOnInit runs once after the component is created to initialize data.

What is the main use of ngOnDestroy?

A Start fetching data

B Clean up resources before component removal

C Detect changes in data

D Render the component view

ngOnDestroy is used to clean up timers, subscriptions, or other resources to prevent memory leaks.

Why should you use lifecycle hooks in Angular?

A To write CSS

B To style components

C To manage component setup and cleanup

D To create new components

Lifecycle hooks help manage important moments like setup and cleanup in a component's life.

Which hook runs after Angular has fully initialized a component's view?

A ngAfterViewInit

B ngOnInit

C ngOnDestroy

D ngOnChanges

ngAfterViewInit runs after the component's view and child views are initialized.

What can happen if you ignore ngOnDestroy when using subscriptions?

A Memory leaks occur

B Component styles break

C App runs faster

D Component never renders

Ignoring ngOnDestroy can cause memory leaks because subscriptions stay active after component removal.

Explain why lifecycle hooks are important in Angular components.

Think about what happens when a component starts and ends.

Describe the roles of ngOnInit and ngOnDestroy hooks.

One runs at start, the other at end.