Angular service base class

angular-service-base.ts

import { HttpHeaders, HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';
import { take } from 'rxjs/operators';

/** common request options */
const _HTTP_OPTIONS = {
    headers: new HttpHeaders({
        'Content-Type': 'application/x-www-form-urlencoded'
    }),
    // withCredentials: true
};

/** get request body by formData (object type) */
function getRequestBody(formData: object) {
    if (formData) {
        const obj = getURLSearchParams(formData);
        return obj.toString();
    }
}
/**
 * constructe URLSearchParams by form data(obejct)
 * limitation: not support complicated form data, namely the properties of form data should be primitive type
 */
function getURLSearchParams(formData: object): URLSearchParams {
    const params = new URLSearchParams();
    if (formData) {
        Object.keys(formData).forEach(p => {
            const val = formData[p];
            if (Array.isArray(val)) {
                // workaround 1: make sure the item of the array are primitive type (work in front-end)
                val.forEach(v => {
                    params.append(p, typeof (v) === 'object' ? JSON.stringify(v) : v);
                });
                // // workaround 2: cast array type to string type(deserialize it in server side)
                // params.append(p, JSON.stringify(val));;
            } else if (typeof val !== 'object') {
                params.append(p, val);
            }
        });
    }
    // // append timestamp to the form body to force query (ignore cache/Relativity platform/server cache)
    // params.append('t', Date.now().toString());
    return params;
}

export class BaseService {
    constructor(
        private http: HttpClient
    ) {
        this.BASE_URL = '/your-app-root-path-here/';
    }
    /** ApiController URL */
    private BASE_URL: string;

    /** sending post request to API  */
    _post(actionName: string, formData?: object): Observable<any> {
        // const url = this._baseURL + actionName;
        const url = `${this.BASE_URL}${actionName}/${Math.round(performance.now())}`;
        return this.http.post(
            url,
            getRequestBody(formData),   // custom
            _HTTP_OPTIONS    // options
        ).pipe(take(1));
    }
}