gistfile1.txt

const data = 'username=' + encodeURIComponent(credentials.username) + '&password=' +
      encodeURIComponent(credentials.password) + '&grant_type=password&scope=read%20write&' +
      'client_secret=' + this.clientSecret + '&client_id=' + this.clientId;

    const headers = new HttpHeaders()
      .set('Content-Type', 'application/x-www-form-urlencoded')
      .set('Accept', 'application/json')
      .set('Authorization', 'Basic ' + this.base64('myapp' + ':' + 'mySecretOAuthSecret'));

    return this.http.post(this.urlLogin, data, {
      headers
    })