[Solved] Identify the error in this facade service method:fetchData() { this.apiService.getData().subscribe(data => { this.data = data; }); return this.data; } | Angular

Angular - Advanced Patterns

Identify the error in this facade service method:

fetchData() {
  this.apiService.getData().subscribe(data => {
    this.data = data;
  });
  return this.data;
}

AUsing arrow function inside subscribe is invalid syntax

BReturns data before subscription completes, causing undefined result

CSubscription should be inside component, not service

DMissing return type annotation causes compile error

Step-by-Step Solution

Solution:

Step 1: Understand asynchronous subscription
The subscribe callback runs later, so this.data is not set immediately.
Step 2: Identify return timing issue
The method returns this.data immediately, likely undefined before data arrives.
Final Answer:
Returns data before subscription completes, causing undefined result -> Option B
Quick Check:
Async subscribe returns undefined early [OK]

Quick Trick: Return inside subscribe or use Observable return [OK]

Common Mistakes:

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