Angular 2 - PERFORMANCE

api.service.ts

import {
    Injectable,
    Injector,
}    from '@angular/core';
import 'rxjs/add/operator/toPromise';

import {Router} from '@angular/router';
import {
    Http,
    RequestOptions,
    Request,
    Headers,
    RequestMethod,
    Response,
    URLSearchParams,

}            from '@angular/http';

import {CONFIG}  from '../shared/app.config';


@Injectable()
export class ApiService {
    private url: string = CONFIG.api.url;

    public constructor(private http: Http, private router: Router, private injector: Injector) {
    }

    public querie(method: string, action: string, params: Object = {}, body: Object = {}, headers: Object = {}, customErrorHandler: Object = {}) {
        method = method.substr(0, 1).toUpperCase() + method.substr(1).toLowerCase();
        if (action[0] === '/') {
            action = action.substr(1);
        }

        let dataHeaders = new Headers();
        for (let key in headers) {
            dataHeaders.append(key, headers[key]);
        }

        let dataSearch = new URLSearchParams();
        for (let key in params) {
            dataSearch.set(key, params[key]);
        }

        let requestOptions = new RequestOptions({
            method: RequestMethod[method],
            url: this.url + action,
            headers: dataHeaders,
            search: dataSearch,
            body: body,
        });

        return this.http.request(new Request(requestOptions)).toPromise().then((res: Response) => {
            return res.json();
        }).catch(this.handleError);
    }

    public get(action: string, params: Object = {}, headers: Object = {}) {
        return this.querie('GET', action, params, null, headers);
    }

    public post(action: string, body: Object = {}) {
        return this.querie('POST', action, null, body);
    }

    public put(action: string, body: Object = {}) {
        return this.querie('PUT', action, null, body);
    }

    public patch(action: string, body: Object = {}) {
        return this.querie('PATCH', action, null, body);
    }

    public delete(action: string, params: Object = {}, headers: Object = {}) {
        return this.querie('DELETE', action, params, null, headers);
    }

    private handleError (error: Response | any) {
        // In a real world app, we might use a remote logging infrastructure
        let errMsg: string;
        if (error instanceof Response) {
            const body = error.json() || '';
            const err = body.error || JSON.stringify(body);
            errMsg = JSON.parse(err);
        } else {
            errMsg = error.message ? error.message : error.toString();
        }
        return Promise.reject(errMsg);
    }
}