An Angular (> 4.3) interceptor to parse dates from server response.

AngularDateHttpInterceptor.ts

import { Injectable } from '@angular/core';
import { HttpRequest, HttpHandler, HttpEvent, HttpInterceptor, HttpErrorResponse, HttpResponse } from '@angular/common/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/do';

@Injectable()
export class AngularDateHttpInterceptor implements HttpInterceptor {
  // Migrated from AngularJS https://raw.githubusercontent.com/Ins87/angular-date-interceptor/master/src/angular-date-interceptor.js
  iso8601 = /^\d{4}-\d\d-\d\dT\d\d:\d\d:\d\d(\.\d+)?(([+-]\d\d:\d\d)|Z)?$/;

  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    return next.handle(req).do((event: HttpEvent<any>) => {
      if (event instanceof HttpResponse) {
        const body = event.body;
        this.convertToDate(body);
      }
    }, (err: any) => {
      if (err instanceof HttpErrorResponse) {
        if (err.status === 401) {
        }
      }
    });
  }

  convertToDate(body) {
    if (body === null || body === undefined) {
      return body;
    }

    if (typeof body !== 'object') {
      return body;
    }

    for (const key of Object.keys(body)) {
      const value = body[key];
      if (this.isIso8601(value)) {
        body[key] = new Date(value);
      } else if (typeof value === 'object') {
        this.convertToDate(value);
      }
    }
  }

  isIso8601(value) {
    if (value === null || value === undefined) {
      return false;
    }

    return this.iso8601.test(value);
  }
}