Which of the following is the correct way to inject a service named DataService into an Angular component's constructor to facilitate testing?

easy📝 Syntax Q3 of 15

Angular - Services and Dependency Injection

Which of the following is the correct way to inject a service named DataService into an Angular component's constructor to facilitate testing?

Aconstructor(private dataService) {}

Bconstructor(dataService: DataService) { this.dataService = dataService; }

Cconstructor(@Inject(DataService) dataService) {}

Dconstructor(private dataService: DataService) {}

Step-by-Step Solution

Solution:

Step 1: Recognize Angular DI syntax
Angular uses constructor parameter properties with access modifiers to inject services.
Step 2: Analyze options
constructor(private dataService: DataService) {} correctly uses private to declare and inject DataService.
Final Answer:
constructor(private dataService: DataService) {} -> Option D
Quick Check:
Private constructor parameter triggers DI injection [OK]

Quick Trick: Use private in constructor to inject services [OK]

Common Mistakes:

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