When working with the Angular HTTP module, whether to use map or switchMap depends on the scenario:
Use map when
You only need to transform the response from an HTTP call.
There is no need to cancel or replace previous requests.
Example:
this.http.get<User>('https://api.example.com/user')
.pipe(map(user => user.name))
.subscribe(name => console.log(name));
Use switchMap when
You need to replace an ongoing request with a new one (e.g., when handling user input or dependent API calls).
It cancels the previous HTTP request if a new one starts before the previous completes.
Example (e.g., search field API call):
this.searchInput.valueChanges.pipe(
debounceTime(300),
switchMap(query => this.http.get<User[]>(`https://api.example.com/search?query=${query}`))
).subscribe(users => console.log(users));
Key Difference:
map transforms data without affecting the stream flow.
switchMap cancels the previous observable and subscribes to a new one.