Angular Architecture & Modules Quiz – 20 Questions with Answers
20 questions · 15 min · Medium
Lifecycle Hooks in Angular
Test your knowledge of Angular lifecycle hooks, including ngOnInit, ngOnChanges, ngDoCheck, ngAfterContentInit, ngAfterContentChecked, ngAfterViewInit, ngAfterViewChecked, and ngOnDestroy.
- 15
- Questions
- 12 min
- Time limit
- Medium
- Difficulty
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All 15 questions and answers Spoilers: this shows the questions and answers. Try the quiz first! Open
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1. What are lifecycle hooks in Angular?
- A. Methods that allow a component to respond to important moments in its lifecycle
- B. Functions used only for HTTP requests
- C. Methods used only to create routes
- D. CSS functions for styling components
Show answer
A. Methods that allow a component to respond to important moments in its lifecycle
Angular lifecycle hooks let components and directives run code at specific stages of their creation, change detection, rendering, and destruction.
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2. Which lifecycle hook is commonly used for initialization logic after Angular has initialized a component's input properties?
- A. ngOnInit
- B. ngOnDestroy
- C. ngAfterViewChecked
- D. ngDoCheck
Show answer
A. ngOnInit
ngOnInit runs once after Angular has initialized the component's input properties.
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3. Which lifecycle hook is called when one or more data-bound input properties change?
- A. ngOnChanges
- B. ngOnInit
- C. ngAfterViewInit
- D. ngOnDestroy
Show answer
A. ngOnChanges
ngOnChanges runs when Angular detects changes to data-bound input properties and receives a SimpleChanges object describing those changes.
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4. What does the ngOnChanges lifecycle hook receive as an argument?
- A. SimpleChanges
- B. ChangeDetector
- C. ComponentRef
- D. ViewChanges
Show answer
A. SimpleChanges
ngOnChanges receives a SimpleChanges object containing information about the current and previous values of changed input properties.
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5. Which lifecycle hook can be used to implement custom change detection logic?
- A. ngDoCheck
- B. ngOnInit
- C. ngAfterContentInit
- D. ngOnDestroy
Show answer
A. ngDoCheck
ngDoCheck runs during Angular's change-detection process and can be used when custom change detection logic is required.
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6. Which lifecycle hook runs once after Angular has initialized content projected into a component?
- A. ngAfterContentInit
- B. ngAfterViewInit
- C. ngOnInit
- D. ngAfterViewChecked
Show answer
A. ngAfterContentInit
ngAfterContentInit runs once after Angular has completed initialization of the component's projected content.
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7. Which lifecycle hook runs after Angular checks the content projected into a component?
- A. ngAfterContentChecked
- B. ngAfterContentInit
- C. ngAfterViewInit
- D. ngOnChanges
Show answer
A. ngAfterContentChecked
ngAfterContentChecked runs after Angular checks the content projected into the component.
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8. Which lifecycle hook runs once after Angular initializes a component's view and child views?
- A. ngAfterViewInit
- B. ngAfterContentInit
- C. ngOnInit
- D. ngDoCheck
Show answer
A. ngAfterViewInit
ngAfterViewInit runs once after Angular has fully initialized the component's view and its child views.
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9. Which lifecycle hook runs after Angular checks a component's view and child views?
- A. ngAfterViewChecked
- B. ngAfterViewInit
- C. ngAfterContentInit
- D. ngOnInit
Show answer
A. ngAfterViewChecked
ngAfterViewChecked runs after Angular has completed a check of the component's view and child views.
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10. Which lifecycle hook is used for cleanup before a component is destroyed?
- A. ngOnDestroy
- B. ngAfterDestroy
- C. ngCleanup
- D. ngDispose
Show answer
A. ngOnDestroy
ngOnDestroy runs immediately before Angular destroys a component or directive and is commonly used for cleanup.
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11. Which task is commonly appropriate to perform in ngOnDestroy?
- A. Cleaning up subscriptions or event listeners
- B. Initializing component inputs
- C. Creating the component's template
- D. Defining route parameters
Show answer
A. Cleaning up subscriptions or event listeners
ngOnDestroy is commonly used to release resources such as subscriptions, timers, or event listeners before a component is destroyed.
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12. How many times does ngOnInit normally run for a component instance?
- A. Once
- B. Every time change detection runs
- C. Every time the component receives an event
- D. Only when the component is destroyed
Show answer
A. Once
ngOnInit runs once after Angular has initialized the component's input properties.
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13. Which lifecycle hook is especially useful when you need access to view-related queries after the view has been initialized?
- A. ngAfterViewInit
- B. ngOnChanges
- C. ngDoCheck
- D. ngOnDestroy
Show answer
A. ngAfterViewInit
ngAfterViewInit runs after the component's view and child views have been initialized, making it useful for view-related initialization.
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14. Which lifecycle hook can run many times during the lifetime of a component?
- A. ngAfterViewChecked
- B. ngOnInit
- C. ngAfterViewInit
- D. ngAfterContentInit
Show answer
A. ngAfterViewChecked
ngAfterViewChecked can run repeatedly whenever Angular performs checks on the component's view.
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15. Which sequence best represents the major lifecycle stages of an Angular component?
- A. Initialization, change detection, view/content checks, and destruction
- B. Compilation, database creation, routing, and deployment
- C. Routing, HTTP request, CSS compilation, and deletion
- D. Template creation, database migration, authentication, and logout
Show answer
A. Initialization, change detection, view/content checks, and destruction
Angular components move through stages that include initialization, change detection and view/content checks, followed eventually by destruction.