[Solved] Why does this code cause a runtime error?import { of } from 'rxjs'; import { map } from 'rxjs/operators'; of(1, 2, 3).pipe( map(x => x.toUpperCase()) ).subscribe(console.log); | Angular

Angular - RxJS Operators

Why does this code cause a runtime error?

import { of } from 'rxjs';
import { map } from 'rxjs/operators';

of(1, 2, 3).pipe(
  map(x => x.toUpperCase())
).subscribe(console.log);

ABecause subscribe() is missing error handling

BBecause map operator is used incorrectly

CBecause of() cannot emit numbers

DBecause numbers do not have a toUpperCase() method

Step-by-Step Solution

Solution:

Step 1: Analyze the emitted values and method called
The observable emits numbers 1, 2, 3 but toUpperCase() is a string method.
Step 2: Understand the runtime error cause
Calling toUpperCase() on a number causes a runtime error because the method does not exist on numbers.
Final Answer:
Because numbers do not have a toUpperCase() method -> Option D
Quick Check:
toUpperCase only works on strings [OK]

Quick Trick: Check method compatibility with data type [OK]

Common Mistakes:

MISTAKES

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Why does this code cause a runtime error?