login(usn: string, psw: string): Observable<boolean> {
        let headers = new Headers({ 'Content-Type': 'application/json' });
        let options = new RequestOptions({ headers: headers });
        let body = JSON.stringify({ username: usn, password: psw });
        return this.http.post('http://localhost:5000/auth', body, options)
            .map((response: Response) => {
                // login successful if there's a jwt token in the response
                let token = response.json() && response.json().token;

                if (token) {
                    // set token property
                    this.token = token;

                    // store username and jwt token in local storage to keep user logged in between page refreshes
                    localStorage.setItem('currentUser', JSON.stringify({ username: usn, token: token }));

                    // return true to indicate successful login
                    return true;
                } else {
                    // return false to indicate failed login
                    return false;
                }
            });
    }

Request URL:http://localhost:5000/auth
Request Method:OPTIONS
Status Code:200 OK
Remote Address:127.0.0.1:5000
Response Headers
view source
Allow:POST, OPTIONS
Content-Length:0
Content-Type:text/html; charset=utf-8
Date:Fri, 30 Dec 2016 22:40:57 GMT
Server:Werkzeug/0.11.13 Python/3.5.2
Request Headers
view source
Accept:*/*
Accept-Encoding:gzip, deflate, sdch, br
Accept-Language:en-US,en;q=0.8,es;q=0.6
Access-Control-Request-Headers:content-type
Access-Control-Request-Method:POST
Connection:keep-alive
Host:localhost:5000
Origin:http://localhost:4200
Referer:http://localhost:4200/
User-Agent:Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36