AngularIntermediate9 min read2026-03-01
Angular HTTP Client & Interceptors
Consume REST APIs in Angular using HttpClient, Bearer token interceptors, and RxJS error operators.
Prerequisites
- Angular Services basics
1. Functional HTTP Interceptor
Attach authorization tokens to outgoing HTTP requests automatically.
typescript
import { HttpInterceptorFn } from '@angular/common/http';
export const authInterceptor: HttpInterceptorFn = (req, next) => {
const token = localStorage.getItem('auth_token');
if (token) {
const cloned = req.clone({
setHeaders: { Authorization: `Bearer ${token}` }
});
return next(cloned);
}
return next(req);
};Best Practices & Architecture Advice
- Always type your HTTP calls (this.http.get<User[]>('/api/users')).
Common Mistakes to Watch Out For
- •Mutating HttpRequest objects directly instead of calling req.clone().
Frequently Asked Questions
Where do I register functional interceptors in modern Angular?
Pass them to provideHttpClient(withInterceptors([authInterceptor])) in app.config.ts.
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