diff --git a/types/mixpanel-browser/index.d.ts b/types/mixpanel-browser/index.d.ts
index 89f7619023..9877637d5b 100644
--- a/types/mixpanel-browser/index.d.ts
+++ b/types/mixpanel-browser/index.d.ts
@@ -3,6 +3,7 @@
 // Definitions by: Carlos López <https://github.com/karlos1337>
 //                 Ricardo Rodrigues <https://github.com/RicardoRodrigues>
 //                 Kristian Randall <https://github.com/randak>
+//                 Dan Wilt <https://github.com/dwilt>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.2
 
@@ -12,86 +13,92 @@ export type PushItem = Array<string | Dict>;
 
 export type Query = string | Element | Element[];
 
-export interface Dict {[key: string]: any; }
-
-export interface RequestOptions {
-  transport?: "xhr" | "sendBeacon";
+export interface Dict {
+    [key: string]: any;
 }
 
-export interface XhrHeadersDef {[header: string]: any; }
+export interface RequestOptions {
+    transport?: 'xhr' | 'sendBeacon';
+}
+
+export interface XhrHeadersDef {
+    [header: string]: any;
+}
 
 export interface HasOptedInOutOptions {
-  persistence_type: Persistence;
-  cookie_prefix: string;
+    persistence_type: Persistence;
+    cookie_prefix: string;
 }
 
 export interface ClearOptOutInOutOptions extends HasOptedInOutOptions {
-  cookie_expiration: number;
-  cross_subdomain_cookie: boolean;
-  secure_cookie: boolean;
+    cookie_expiration: number;
+    cross_subdomain_cookie: boolean;
+    secure_cookie: boolean;
 }
 
 export interface InTrackingOptions extends ClearOptOutInOutOptions {
-  track: () => void;
-  track_event_name: string;
-  track_event_properties: Dict;
+    track: () => void;
+    track_event_name: string;
+    track_event_properties: Dict;
 }
 
 export interface OutTrackingOptions extends ClearOptOutInOutOptions {
-  delete_user: boolean;
+    delete_user: boolean;
 }
 
 export interface Config {
-  api_host: string;
-  api_method: string;
-  api_transport: string;
-  app_host: string;
-  autotrack: boolean;
-  cdn: string;
-  cookie_domain: string;
-  cross_site_cookie: boolean;
-  cross_subdomain_cookie: boolean;
-  persistence: Persistence;
-  persistence_name: string;
-  cookie_name: string;
-  loaded: (mixpanel: Mixpanel) => void;
-  store_google: boolean;
-  save_referrer: boolean;
-  test: boolean;
-  verbose: boolean;
-  img: boolean;
-  track_pageview: boolean;
-  debug: boolean;
-  track_links_timeout: number;
-  cookie_expiration: number;
-  upgrade: boolean;
-  disable_persistence: boolean;
-  disable_cookie: boolean;
-  disable_notifications: boolean;
-  secure_cookie: boolean;
-  ip: boolean;
-  property_blacklist: string[];
-  xhr_headers: XhrHeadersDef;
-  opt_out_tracking_by_default: boolean;
-  opt_out_persistence_by_default: boolean;
-  opt_out_tracking_persistence_type: Persistence;
-  opt_out_tracking_cookie_prefix: string;
-  inapp_protocol: string;
-  inapp_link_new_window: boolean;
-  ignore_dnt: boolean;
-  batch_requests: boolean;
-  batch_size: number;
-  batch_flush_interval_ms: number;
-  batch_request_timeout_ms: number;
+    api_host: string;
+    api_method: string;
+    api_transport: string;
+    app_host: string;
+    autotrack: boolean;
+    cdn: string;
+    cookie_domain: string;
+    cross_site_cookie: boolean;
+    cross_subdomain_cookie: boolean;
+    persistence: Persistence;
+    persistence_name: string;
+    cookie_name: string;
+    loaded: (mixpanel: Mixpanel) => void;
+    store_google: boolean;
+    save_referrer: boolean;
+    test: boolean;
+    verbose: boolean;
+    img: boolean;
+    track_pageview: boolean;
+    debug: boolean;
+    track_links_timeout: number;
+    cookie_expiration: number;
+    upgrade: boolean;
+    disable_persistence: boolean;
+    disable_cookie: boolean;
+    disable_notifications: boolean;
+    secure_cookie: boolean;
+    ip: boolean;
+    property_blacklist: string[];
+    xhr_headers: XhrHeadersDef;
+    opt_out_tracking_by_default: boolean;
+    opt_out_persistence_by_default: boolean;
+    opt_out_tracking_persistence_type: Persistence;
+    opt_out_tracking_cookie_prefix: string;
+    inapp_protocol: string;
+    inapp_link_new_window: boolean;
+    ignore_dnt: boolean;
+    batch_requests: boolean;
+    batch_size: number;
+    batch_flush_interval_ms: number;
+    batch_request_timeout_ms: number;
 }
 
-export type VerboseResponse = {
-  status: 1;
-  error: null;
-} | {
-  status: 0;
-  error: string;
-};
+export type VerboseResponse =
+    | {
+          status: 1;
+          error: null;
+      }
+    | {
+          status: 0;
+          error: string;
+      };
 
 export type NormalResponse = 1 | 0;
 
@@ -100,55 +107,83 @@ export type Response = VerboseResponse | NormalResponse;
 export type Callback = (response: Response) => void;
 
 export interface People {
-  set(prop: string, to: any, callback?: Callback): void;
-  set(prop: Dict, callback?: Callback): void;
-  set_once(prop: string, to: any, callback?: Callback): void;
-  set_once(prop: Dict, callback?: Callback): void;
-  unset(prop: string[] | string, callback?: Callback): void;
-  increment(prop: string | Dict, callback?: Callback): void;
-  increment(prop: string, by: number, callback?: Callback): void;
-  remove(prop: string, value: any, callback?: Callback): void;
-  remove(prop: Dict, callback?: Callback): void;
-  append(prop: string, value: any, callback?: Callback): void;
-  append(prop: Dict, callback?: Callback): void;
-  union(prop: string, value: any, callback?: Callback): void;
-  union(prop: Dict, callback?: Callback): void;
-  track_charge(amount: number, propertiesOrCallback?: Dict | Callback, callback?: Callback): void;
-  clear_charges(callback?: Callback): void;
-  delete_user(): void;
+    set(prop: string, to: any, callback?: Callback): void;
+    set(prop: Dict, callback?: Callback): void;
+    set_once(prop: string, to: any, callback?: Callback): void;
+    set_once(prop: Dict, callback?: Callback): void;
+    unset(prop: string[] | string, callback?: Callback): void;
+    increment(prop: string | Dict, callback?: Callback): void;
+    increment(prop: string, by: number, callback?: Callback): void;
+    remove(prop: string, value: any, callback?: Callback): void;
+    remove(prop: Dict, callback?: Callback): void;
+    append(prop: string, value: any, callback?: Callback): void;
+    append(prop: Dict, callback?: Callback): void;
+    union(prop: string, value: any, callback?: Callback): void;
+    union(prop: Dict, callback?: Callback): void;
+    track_charge(amount: number, propertiesOrCallback?: Dict | Callback, callback?: Callback): void;
+    clear_charges(callback?: Callback): void;
+    delete_user(): void;
+}
+
+export interface Group {
+    remove(list_name: string, value: string, callback?: Callback): Group;
+    set<Prop extends string | Dict>(
+        prop: Prop,
+        to?: Prop extends string ? string : undefined,
+        callback?: Callback,
+    ): Group;
+    setOnce<Prop extends string | Dict>(
+        prop: Prop,
+        to?: Prop extends string ? string : undefined,
+        callback?: Callback,
+    ): Group;
+    union(list_name: string, values: Array<string | number>, callback?: Callback): Group;
+    unset(prop: string, callback?: Callback): void;
 }
 
 export interface Mixpanel {
-  alias(alias: string, original?: string): void;
-  clear_opt_in_out_tracking(options?: Partial<ClearOptOutInOutOptions>): void;
-  disable(events?: string[]): void;
-  get_config(prop_name?: string): any;
-  get_distinct_id(): any;
-  get_property(property_name: string): any;
-  has_opted_in_tracking(options?: Partial<HasOptedInOutOptions>): boolean;
-  has_opted_out_tracking(options?: Partial<HasOptedInOutOptions>): boolean;
-  identify(unique_id?: string): any;
-  init(token: string, config?: Partial<Config>, name?: string): Mixpanel;
-  opt_in_tracking(options?: Partial<InTrackingOptions>): void;
-  opt_out_tracking(options?: Partial<OutTrackingOptions>): void;
-  push(item: PushItem): void;
-  register(props: Dict, days?: number): void;
-  register_once(props: Dict, default_value?: any, days?: number): void;
-  reset(): void;
-  set_config(config: Partial<Config>): void;
-  time_event(event_name: string): void;
-  track(event_name: string, properties?: Dict, optionsOrCallback?: RequestOptions | Callback, callback?: Callback): void;
-  track_forms(query: Query, event_name: string, properties?: Dict | (() => void)): void;
-  track_links(query: Query, event_name: string, properties?: Dict | (() => void)): void;
-  unregister(property: string): void;
-  people: People;
+    add_group(group_key: string, group_id: string, callback?: Callback): void;
+    alias(alias: string, original?: string): void;
+    clear_opt_in_out_tracking(options?: Partial<ClearOptOutInOutOptions>): void;
+    disable(events?: string[]): void;
+    get_config(prop_name?: string): any;
+    get_distinct_id(): any;
+    get_group(group_key: string, group_id: string): Group;
+    get_property(property_name: string): any;
+    has_opted_in_tracking(options?: Partial<HasOptedInOutOptions>): boolean;
+    has_opted_out_tracking(options?: Partial<HasOptedInOutOptions>): boolean;
+    identify(unique_id?: string): any;
+    init(token: string, config?: Partial<Config>, name?: string): Mixpanel;
+    opt_in_tracking(options?: Partial<InTrackingOptions>): void;
+    opt_out_tracking(options?: Partial<OutTrackingOptions>): void;
+    push(item: PushItem): void;
+    register(props: Dict, days?: number): void;
+    register_once(props: Dict, default_value?: any, days?: number): void;
+    remove_group(group_key: string, group_ids: string | string[] | number | number[], callback?: Callback): void;
+    reset(): void;
+    set_config(config: Partial<Config>): void;
+    set_group(group_key: string, group_ids: string | string[] | number | number[], callback?: Callback): void;
+    time_event(event_name: string): void;
+    track(
+        event_name: string,
+        properties?: Dict,
+        optionsOrCallback?: RequestOptions | Callback,
+        callback?: Callback,
+    ): void;
+    track_forms(query: Query, event_name: string, properties?: Dict | (() => void)): void;
+    track_links(query: Query, event_name: string, properties?: Dict | (() => void)): void;
+    track_with_groups(event_name: string, properties: Dict, groups: Dict, callback?: Callback): void;
+    unregister(property: string): void;
+    people: People;
 }
 
+export function add_group(group_key: string, group_id: string, callback?: Callback): void;
 export function alias(alias: string, original?: string): void;
 export function clear_opt_in_out_tracking(options?: Partial<ClearOptOutInOutOptions>): void;
 export function disable(events?: string[]): void;
 export function get_config(prop_name?: string): any;
 export function get_distinct_id(): any;
+export function get_group(group_key: string, group_id: string): Group;
 export function get_property(property_name: string): any;
 export function has_opted_in_tracking(options?: Partial<HasOptedInOutOptions>): boolean;
 export function has_opted_out_tracking(options?: Partial<HasOptedInOutOptions>): boolean;
@@ -159,12 +194,28 @@ export function opt_out_tracking(options?: Partial<OutTrackingOptions>): void;
 export function push(item: PushItem): void;
 export function register(props: Dict, days?: number): void;
 export function register_once(props: Dict, default_value?: any, days?: number): void;
+export function remove_group(
+    group_key: string,
+    group_ids: string | string[] | number | number[],
+    callback?: Callback,
+): void;
 export function reset(): void;
 export function set_config(config: Partial<Config>): void;
+export function set_group(
+    group_key: string,
+    group_ids: string | string[] | number | number[],
+    callback?: Callback,
+): void;
 export function time_event(event_name: string): void;
-export function track(event_name: string, properties?: Dict, optionsOrCallback?: RequestOptions | Callback, callback?: Callback): void;
+export function track(
+    event_name: string,
+    properties?: Dict,
+    optionsOrCallback?: RequestOptions | Callback,
+    callback?: Callback,
+): void;
 export function track_forms(query: Query, event_name: string, properties?: Dict | (() => void)): void;
 export function track_links(query: Query, event_name: string, properties?: Dict | (() => void)): void;
+export function track_with_groups(event_name: string, properties: Dict, groups: Dict, callback?: Callback): void;
 export function unregister(property: string): void;
 export const people: People;
 
diff --git a/types/mixpanel-browser/mixpanel-browser-tests.ts b/types/mixpanel-browser/mixpanel-browser-tests.ts
index 10983ca625..14b6019446 100644
--- a/types/mixpanel-browser/mixpanel-browser-tests.ts
+++ b/types/mixpanel-browser/mixpanel-browser-tests.ts
@@ -4,64 +4,68 @@ const lib = mixpanel.init('new token', { secure_cookie: true }, 'library_name');
 lib.track('event name');
 mixpanel.push(['register', { a: 'b' }]);
 mixpanel.disable();
-mixpanel.track('Registered', {Gender: 'Male', Age: 21});
+mixpanel.track('Registered', { Gender: 'Male', Age: 21 });
 mixpanel.track_links('#nav', 'Clicked Nav Link');
 mixpanel.track_forms('#register', 'Created Account');
 mixpanel.time_event('Registered');
-mixpanel.track('Registered', {Gender: 'Male', Age: 21});
-mixpanel.track('Left page', {duration_seconds: 35}, {transport: 'sendBeacon'});
-mixpanel.track('Left page', { duration_seconds: 35 }, () => { /* callback function */ });
-mixpanel.track('Left page', { duration_seconds: 35 }, { transport: 'sendBeacon' }, () => { /* callback function */ });
-mixpanel.track('Left page', { duration_seconds: 35 }, (response) => {
+mixpanel.track('Registered', { Gender: 'Male', Age: 21 });
+mixpanel.track('Left page', { duration_seconds: 35 }, { transport: 'sendBeacon' });
+mixpanel.track('Left page', { duration_seconds: 35 }, () => {
+    /* callback function */
+});
+mixpanel.track('Left page', { duration_seconds: 35 }, { transport: 'sendBeacon' }, () => {
+    /* callback function */
+});
+mixpanel.track('Left page', { duration_seconds: 35 }, response => {
     if (response === 1) {
     } else if (response === 0) {
     } else if (response.status === 1 && response.error === null) {
     } else if (response.status === 0 && response.error.includes('bad')) {
     }
 });
-mixpanel.register({Gender: 'Female'});
+mixpanel.register({ Gender: 'Female' });
 mixpanel.register({
-  Email: 'jdoe@example.com',
-  'Account Type': 'Free'
+    Email: 'jdoe@example.com',
+    'Account Type': 'Free',
 });
 mixpanel.register_once({
-  'First Login Date': new Date().toISOString()
+    'First Login Date': new Date().toISOString(),
 });
 mixpanel.init('YOUR PROJECT TOKEN', {
-  loaded: (mixpanel) => {
-      const distinct_id = mixpanel.get_distinct_id();
-  }
+    loaded: mixpanel => {
+        const distinct_id = mixpanel.get_distinct_id();
+    },
 });
 mixpanel.alias('new_id', 'existing_id');
 mixpanel.alias('newer_id', 'new_id');
 mixpanel.init('YOUR PROJECT TOKEN', {
-  loaded: (mixpanel) => {
-      const user_id = mixpanel.get_property('user_id');
-  }
+    loaded: mixpanel => {
+        const user_id = mixpanel.get_property('user_id');
+    },
 });
 mixpanel.opt_in_tracking();
 mixpanel.opt_in_tracking({
     track_event_name: 'User opted in',
     track_event_properties: {
-        Email: 'jdoe@example.com'
+        Email: 'jdoe@example.com',
     },
     cookie_expiration: 30,
-    secure_cookie: true
+    secure_cookie: true,
 });
 mixpanel.opt_out_tracking();
 mixpanel.opt_out_tracking({
     cookie_expiration: 30,
-    secure_cookie: true
+    secure_cookie: true,
 });
 const has_opted_in = mixpanel.has_opted_in_tracking();
 const has_opted_out = mixpanel.has_opted_out_tracking();
 mixpanel.clear_opt_in_out_tracking();
 mixpanel.clear_opt_in_out_tracking({
     cookie_expiration: 30,
-    secure_cookie: true
+    secure_cookie: true,
 });
 mixpanel.people.set('gender', 'm');
-mixpanel.people.set('gender', 'm', (response) => {
+mixpanel.people.set('gender', 'm', response => {
     if (response === 1) {
     } else if (response === 0) {
     } else if (response.status === 1 && response.error === null) {
@@ -71,22 +75,25 @@ mixpanel.people.set('gender', 'm', (response) => {
 mixpanel.people.set({
     Company: 'Acme',
     Plan: 'Premium',
-    'Upgrade date': new Date()
-});
-mixpanel.people.set({
-    Company: 'Acme',
-    Plan: 'Premium',
-    'Upgrade date': new Date()
-}, (response) => {
-    if (response === 1) {
-    } else if (response === 0) {
-    } else if (response.status === 1 && response.error === null) {
-    } else if (response.status === 0 && response.error.includes('bad')) {
-    }
+    'Upgrade date': new Date(),
 });
+mixpanel.people.set(
+    {
+        Company: 'Acme',
+        Plan: 'Premium',
+        'Upgrade date': new Date(),
+    },
+    response => {
+        if (response === 1) {
+        } else if (response === 0) {
+        } else if (response.status === 1 && response.error === null) {
+        } else if (response.status === 0 && response.error.includes('bad')) {
+        }
+    },
+);
 
 mixpanel.people.set_once('First Login Date', new Date());
-mixpanel.people.set_once('First Login Date', new Date(), (response) => {
+mixpanel.people.set_once('First Login Date', new Date(), response => {
     if (response === 1) {
     } else if (response === 0) {
     } else if (response.status === 1 && response.error === null) {
@@ -95,22 +102,25 @@ mixpanel.people.set_once('First Login Date', new Date(), (response) => {
 });
 mixpanel.people.set_once({
     'First Login Date': new Date(),
-    'Starting Plan': 'Premium'
-});
-mixpanel.people.set_once({
-    'First Login Date': new Date(),
-    'Starting Plan': 'Premium'
-}, (response) => {
-    if (response === 1) {
-    } else if (response === 0) {
-    } else if (response.status === 1 && response.error === null) {
-    } else if (response.status === 0 && response.error.includes('bad')) {
-    }
+    'Starting Plan': 'Premium',
 });
+mixpanel.people.set_once(
+    {
+        'First Login Date': new Date(),
+        'Starting Plan': 'Premium',
+    },
+    response => {
+        if (response === 1) {
+        } else if (response === 0) {
+        } else if (response.status === 1 && response.error === null) {
+        } else if (response.status === 0 && response.error.includes('bad')) {
+        }
+    },
+);
 
 mixpanel.people.unset('gender');
 mixpanel.people.unset(['gender', 'Company']);
-mixpanel.people.unset(['gender', 'Company'], (response) => {
+mixpanel.people.unset(['gender', 'Company'], response => {
     if (response === 1) {
     } else if (response === 0) {
     } else if (response.status === 1 && response.error === null) {
@@ -119,7 +129,7 @@ mixpanel.people.unset(['gender', 'Company'], (response) => {
 });
 
 mixpanel.people.increment('page_views', 1);
-mixpanel.people.increment('page_views', 1, (response) => {
+mixpanel.people.increment('page_views', 1, response => {
     if (response === 1) {
     } else if (response === 0) {
     } else if (response.status === 1 && response.error === null) {
@@ -127,7 +137,7 @@ mixpanel.people.increment('page_views', 1, (response) => {
     }
 });
 mixpanel.people.increment('page_views');
-mixpanel.people.increment('page_views', (response) => {
+mixpanel.people.increment('page_views', response => {
     if (response === 1) {
     } else if (response === 0) {
     } else if (response.status === 1 && response.error === null) {
@@ -137,21 +147,24 @@ mixpanel.people.increment('page_views', (response) => {
 mixpanel.people.increment('credits_left', -1);
 mixpanel.people.increment({
     counter1: 1,
-    counter2: 6
-});
-mixpanel.people.increment({
-    counter1: 1,
-    counter2: 6
-}, (response) => {
-    if (response === 1) {
-    } else if (response === 0) {
-    } else if (response.status === 1 && response.error === null) {
-    } else if (response.status === 0 && response.error.includes('bad')) {
-    }
+    counter2: 6,
 });
+mixpanel.people.increment(
+    {
+        counter1: 1,
+        counter2: 6,
+    },
+    response => {
+        if (response === 1) {
+        } else if (response === 0) {
+        } else if (response.status === 1 && response.error === null) {
+        } else if (response.status === 0 && response.error.includes('bad')) {
+        }
+    },
+);
 
 mixpanel.people.remove('School', 'UCB');
-mixpanel.people.remove('School', 'UCB', (response) => {
+mixpanel.people.remove('School', 'UCB', response => {
     if (response === 1) {
     } else if (response === 0) {
     } else if (response.status === 1 && response.error === null) {
@@ -161,18 +174,21 @@ mixpanel.people.remove('School', 'UCB', (response) => {
 mixpanel.people.remove({
     School: 'UCB',
 });
-mixpanel.people.remove({
-    School: 'UCB',
-}, (response) => {
-    if (response === 1) {
-    } else if (response === 0) {
-    } else if (response.status === 1 && response.error === null) {
-    } else if (response.status === 0 && response.error.includes('bad')) {
-    }
-});
+mixpanel.people.remove(
+    {
+        School: 'UCB',
+    },
+    response => {
+        if (response === 1) {
+        } else if (response === 0) {
+        } else if (response.status === 1 && response.error === null) {
+        } else if (response.status === 0 && response.error.includes('bad')) {
+        }
+    },
+);
 
 mixpanel.people.append('pages_visited', 'homepage');
-mixpanel.people.append('pages_visited', 'homepage', (response) => {
+mixpanel.people.append('pages_visited', 'homepage', response => {
     if (response === 1) {
     } else if (response === 0) {
     } else if (response.status === 1 && response.error === null) {
@@ -181,21 +197,24 @@ mixpanel.people.append('pages_visited', 'homepage', (response) => {
 });
 mixpanel.people.append({
     list1: 'bob',
-    list2: 123
-});
-mixpanel.people.append({
-    list1: 'bob',
-    list2: 123
-}, (response) => {
-    if (response === 1) {
-    } else if (response === 0) {
-    } else if (response.status === 1 && response.error === null) {
-    } else if (response.status === 0 && response.error.includes('bad')) {
-    }
+    list2: 123,
 });
+mixpanel.people.append(
+    {
+        list1: 'bob',
+        list2: 123,
+    },
+    response => {
+        if (response === 1) {
+        } else if (response === 0) {
+        } else if (response.status === 1 && response.error === null) {
+        } else if (response.status === 0 && response.error.includes('bad')) {
+        }
+    },
+);
 
 mixpanel.people.union('pages_visited', 'homepage');
-mixpanel.people.union('pages_visited', 'homepage', (response) => {
+mixpanel.people.union('pages_visited', 'homepage', response => {
     if (response === 1) {
     } else if (response === 0) {
     } else if (response.status === 1 && response.error === null) {
@@ -204,45 +223,52 @@ mixpanel.people.union('pages_visited', 'homepage', (response) => {
 });
 mixpanel.people.union({
     list1: 'bob',
-    list2: 123
+    list2: 123,
 });
+mixpanel.people.union(
+    {
+        list1: 'bob',
+        list2: 123,
+    },
+    response => {
+        if (response === 1) {
+        } else if (response === 0) {
+        } else if (response.status === 1 && response.error === null) {
+        } else if (response.status === 0 && response.error.includes('bad')) {
+        }
+    },
+);
 mixpanel.people.union({
-    list1: 'bob',
-    list2: 123
-}, (response) => {
-    if (response === 1) {
-    } else if (response === 0) {
-    } else if (response.status === 1 && response.error === null) {
-    } else if (response.status === 0 && response.error.includes('bad')) {
-    }
-});
-mixpanel.people.union({
-    list1: ['bob', 'billy']
+    list1: ['bob', 'billy'],
 });
 
 mixpanel.people.track_charge(50);
-mixpanel.people.track_charge(50, (response) => {
+mixpanel.people.track_charge(50, response => {
     if (response === 1) {
     } else if (response === 0) {
     } else if (response.status === 1 && response.error === null) {
     } else if (response.status === 0 && response.error.includes('bad')) {
     }
 });
-mixpanel.people.track_charge(30.50, {
-    $time: new Date('jan 1 2012')
-});
-mixpanel.people.track_charge(30.50, {
-    $time: new Date('jan 1 2012')
-}, (response) => {
-    if (response === 1) {
-    } else if (response === 0) {
-    } else if (response.status === 1 && response.error === null) {
-    } else if (response.status === 0 && response.error.includes('bad')) {
-    }
+mixpanel.people.track_charge(30.5, {
+    $time: new Date('jan 1 2012'),
 });
+mixpanel.people.track_charge(
+    30.5,
+    {
+        $time: new Date('jan 1 2012'),
+    },
+    response => {
+        if (response === 1) {
+        } else if (response === 0) {
+        } else if (response.status === 1 && response.error === null) {
+        } else if (response.status === 0 && response.error.includes('bad')) {
+        }
+    },
+);
 
 mixpanel.people.clear_charges();
-mixpanel.people.clear_charges((response) => {
+mixpanel.people.clear_charges(response => {
     if (response === 1) {
     } else if (response === 0) {
     } else if (response.status === 1 && response.error === null) {
@@ -253,3 +279,62 @@ mixpanel.people.delete_user();
 mixpanel.init('YOUR PROJECT TOKEN', {
     ignore_dnt: true,
 });
+mixpanel.add_group('test', 'id');
+mixpanel.get_group('test', 'id');
+mixpanel.remove_group('test', 'id');
+mixpanel.set_group('test', ['some-value'], response => {
+    if (response === 1) {
+    } else if (response === 0) {
+    } else if (response.status === 1 && response.error === null) {
+    } else if (response.status === 0 && response.error.includes('bad')) {
+    }
+});
+mixpanel.get_group('test', 'id').set('prop', 'value', response => {
+    if (response === 1) {
+    } else if (response === 0) {
+    } else if (response.status === 1 && response.error === null) {
+    } else if (response.status === 0 && response.error.includes('bad')) {
+    }
+});
+mixpanel.get_group('test', 'id').set(
+    {
+        name: 'Name',
+    },
+    undefined,
+    response => {
+        if (response === 1) {
+        } else if (response === 0) {
+        } else if (response.status === 1 && response.error === null) {
+        } else if (response.status === 0 && response.error.includes('bad')) {
+        }
+    },
+);
+mixpanel.get_group('test', 'id').setOnce('prop', 'value', response => {
+    if (response === 1) {
+    } else if (response === 0) {
+    } else if (response.status === 1 && response.error === null) {
+    } else if (response.status === 0 && response.error.includes('bad')) {
+    }
+});
+mixpanel.get_group('test', 'id').remove('prop', 'value', response => {
+    if (response === 1) {
+    } else if (response === 0) {
+    } else if (response.status === 1 && response.error === null) {
+    } else if (response.status === 0 && response.error.includes('bad')) {
+    }
+});
+mixpanel.get_group('test', 'id').union('prop', ['value'], response => {
+    if (response === 1) {
+    } else if (response === 0) {
+    } else if (response.status === 1 && response.error === null) {
+    } else if (response.status === 0 && response.error.includes('bad')) {
+    }
+});
+mixpanel.get_group('test', 'id').unset('prop');
+mixpanel.track_with_groups('event', { name: 'Name' }, { group: ['value'] }, response => {
+    if (response === 1) {
+    } else if (response === 0) {
+    } else if (response.status === 1 && response.error === null) {
+    } else if (response.status === 0 && response.error.includes('bad')) {
+    }
+});