insertService.ts

import { Injectable } from '@angular/core';
import { Http, URLSearchParams } from '@angular/http';
import { Observable } from 'rxjs/Observable';
import { Subject } from 'rxjs/Subject';
import { User } from '../model/user';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';

@Injectable()
export class UserService {
    
    constructor(private http: Http) { 
    }

    insertNewUser(user:User): Observable<any>{
        return this.http.post("http://localhost:3000/insertUser", user)
            .map((res:any) => {
                return res.json();
            })
            .catch((error:any) => {
                return Observable.throw(error.json ? error.json().error : error || 'Server error')
            }); 
    }
}