Node.js SDK

The Node.js SDK lets you send events to Amplitude. This library is open-source, check it out on GitHub.

Getting started¶

Use this quickstart guide to get started with Amplitude Node SDK.

Usage¶

Initialize the SDK¶

Initialization is necessary before any instrumentation is done. The API key for your Amplitude project is required. The SDK can be used anywhere after it's initialized anywhere in an application.

import { init } from '@amplitude/analytics-node';

// Option 1, initialize with API_KEY only
init(API_KEY);

// Option 2, initialize including configuration
init(API_KEY, {
  flushIntervalMillis: 30 * 1000, // Sets request interval to 30s
});

Configuration¶

Configure batching behavior¶

To support high-performance environments, the SDK sends events in batches. Every event logged by the track method is queued in memory. Events are flushed in batches in background. You can customize batch behavior with flushQueueSize and flushIntervalMillis. By default, the serverUrl will be https://api2.amplitude.com/2/httpapi. For customers who want to send large batches of data at a time, set useBatch to true to set setServerUrl to batch event upload API https://api2.amplitude.com/batch. Both the regular mode and the batch mode use the same events upload threshold and flush time intervals.

import * as amplitude from '@amplitude/analytics-node';

amplitude.init(API_KEY, {
  // Events queued in memory will flush when number of events exceed upload threshold
  // Default value is 30
  flushQueueSize: 50, 
  // Events queue will flush every certain milliseconds based on setting
  // Default value is 10000 milliseconds
  flushIntervalMillis: 20000,
});

EU data residency¶

You can configure the server zone when initializing the client for sending data to Amplitude's EU servers. The SDK sends data based on the server zone if it's set.

import * as amplitude from '@amplitude/analytics-node';

amplitude.init(API_KEY, {
  serverZone: amplitude.Types.ServerZone.EU,
});

Debugging¶

You can control the level of logs printed to the developer console.

• 'None': Suppresses all log messages.
• 'Error': Shows error messages only.
• 'Warn': Shows error messages and warnings. This is the default value if logLevel isn't explicitly specified.
• 'Verbose': Shows informative messages.
• 'Debug': Shows error messages, warnings, and informative messages that may be useful for debugging, including the function context information for all SDK public method invocations. This logging mode is only suggested to be used in development phases.

Set the log level by configuring the logLevel with the level you want.

amplitude.init(AMPLITUDE_API_KEY, {
  logLevel: amplitude.Types.LogLevel.Warn,
});

The default logger outputs log to the developer console. You can provide your own logger implementation based on the Logger interface for any customization purpose. For example, collecting any error messages from the SDK in a production environment.

Set the logger by configuring the loggerProvider with your own implementation.

amplitude.init(AMPLITUDE_API_KEY, {
  loggerProvider: new MyLogger(),
});

Debug Mode¶

Enable the debug mode by setting the logLevel to "Debug", for example:

amplitude.init(AMPLITUDE_API_KEY, {
  logLevel: amplitude.Types.LogLevel.Debug,
});

With the default logger, extra function context information will be output to the developer console when invoking any SDK public method, including:

• 'type': Category of this context, e.g., "invoke public method".
• 'name': Name of invoked function, e.g., "setUserId".
• 'args': Arguments of the invoked function.
• 'stacktrace': Stacktrace of the invoked function.
• 'time': Start and end timestamp of the function invocation.
• 'states': Useful internal states snapshot before and after the function invocation.

Tracking an event¶

Events represent how users interact with your application. For example, "Button Clicked" may be an action you want to note.

import { track } from '@amplitude/analytics-node';

// Track a basic event
track('Button Clicked', undefined, {
  user_id: 'user@amplitude.com',
});

// Track events with optional properties
const eventProperties = {
  buttonColor: 'primary',
};
track('Button Clicked', eventProperties, {
  user_id: 'user@amplitude.com',
});

Tracking events to multiple projects¶

If you need to log events to multiple Amplitude projects, you'll need to create separate instances for each Amplitude project. Then, pass the instance variables to wherever you want to call Amplitude. Each instance allows for independent apiKeys, userIds, deviceIds, and settings.

import * as amplitude from '@amplitude/analytics-node';

const defaultInstance = amplitude.createInstance();
defaultInstance.init(API_KEY_DEFAULT);

const envInstance = amplitude.createInstance();
envInstance.init(API_KEY_ENV, {
  instanceName: 'env',
});

User properties¶

User properties help you understand your users at the time they performed some action within your app such as their device details, their preferences, or language.

Identify is for setting the user properties of a particular user without sending any event. The SDK supports the operations set, setOnce, unset, add, append, prepend, preInsert, postInsert, and remove on individual user properties. The operations are declared via a provided Identify interface. Chain together multiple operations together in a single Identify object. The Identify object is then passed to the Amplitude client to send to the server.

Set a user property¶

The Identify object provides controls over setting user properties. An Identify object must first be instantiated, then Identify methods can be called on it, and finally the client makes a call with the Identify object.

import { identify, Identify } from '@amplitude/analytics-node';

const identifyObj = new Identify();
identify(identifyObj, {
  user_id: 'user@amplitude.com',
});

Identify.set¶

This method sets the value of a user property. For example, you can set a role property of a user.

import { Identify, identify } from '@amplitude/analytics-node';

const identifyObj = new Identify();
identifyObj.set('location', 'LAX');

identify(identifyObj, {
  user_id: 'user@amplitude.com',
});

Identify.setOnce¶

This method sets the value of a user property only once. Subsequent calls using setOnce() are ignored. For example, you can set an initial login method for a user and since only the initial value is tracked, setOnce() ignores subsequent calls.

import { Identify, identify } from '@amplitude/analytics-node';

const identifyObj = new Identify();
identifyObj.setOnce('initial-location', 'SFO');

identify(identifyObj, {
  user_id: 'user@amplitude.com',
});

Identify.add¶

This method increments a user property by some numerical value. If the user property doesn't have a value set yet, it's initialized to 0 before being incremented. For example, you can track a user's travel count.

import { Identify, identify } from '@amplitude/analytics-node';

const identifyObj = new Identify();
identifyObj.add('travel-count', 1);

identify(identifyObj, {
  user_id: 'user@amplitude.com',
});

Arrays in user properties¶

Arrays can be used as user properties. You can directly set arrays or use prepend, append, preInsert and postInsert to generate an array.

Identify.prepend¶

This method prepends a value or values to a user property array. If the user property doesn't have a value set yet, it's initialized to an empty list before the new values are prepended.

import { Identify, identify } from '@amplitude/analytics-node';

const identifyObj = new Identify();
identifyObj.prepend('visited-locations', 'LAX');

identify(identifyObj, {
  user_id: 'user@amplitude.com',
});

Identify.append¶

This method appends a value or values to a user property array. If the user property doesn't have a value set yet, it's initialized to an empty list before the new values are prepended.

import { Identify, identify } from '@amplitude/analytics-node';

const identifyObj = new Identify();
identifyObj.append('visited-locations', 'SFO');

identify(identifyObj, {
  user_id: 'user@amplitude.com',
});

Identify.preInsert¶

This method pre-inserts a value or values to a user property if it doesn't exist in the user property yet. Pre-insert means inserting the value at the beginning of a given list. If the user property doesn't have a value set yet, it's initialized to an empty list before the new values are pre-inserted. If the user property has an existing value, it's a no operation.

import { Identify, identify } from '@amplitude/analytics-node';

const identifyObj = new Identify();
identifyObj.preInsert('unique-locations', 'LAX');

identify(identifyObj, {
  user_id: 'user@amplitude.com',
});

Identify.postInsert¶

This method post-inserts a value or values to a user property if it doesn't exist in the user property yet. Post-insert means inserting the value at the end of a given list. If the user property doesn't have a value set yet, it's initialized to an empty list before the new values are post-inserted. If the user property has an existing value, it's a no operation.

import { Identify, identify } from '@amplitude/analytics-node';

const identifyObj = new Identify();
identifyObj.postInsert('unique-locations', 'SFO');

identify(identifyObj, {
  user_id: 'user@amplitude.com',
});

Identify.remove¶

This method removes a value or values to a user property if it exists in the user property. Remove means remove the existing value from the given list. If the item doesn't exist in the user property, it's a no operation.

import { Identify, identify } from '@amplitude/analytics-node';

const identifyObj = new Identify();
identifyObj.remove('unique-locations', 'JFK')

identify(identifyObj, {
  user_id: 'user@amplitude.com',
});

User groups¶

Amplitude supports assigning users to groups and performing queries, such as Count by Distinct, on those groups. If at least one member of the group has performed the specific event, then the count includes the group.

For example, you want to group your users based on what organization they're in by using an 'orgId'. Joe is in 'orgId' '10', and Sue is in 'orgId' '15'. Sue and Joe both perform a certain event. You can query their organizations in the Event Segmentation Chart.

When setting groups, define a groupType and groupName. In the previous example, 'orgId' is the groupType and '10' and '15' are the values for groupName. Another example of a groupType could be 'sport' with groupName values like 'tennis' and 'baseball'.

Setting a group also sets the groupType:groupName as a user property, and overwrites any existing groupName value set for that user's groupType, and the corresponding user property value. groupType is a string, and groupName can be either a string or an array of strings to indicate that a user is in multiple groups.

import { setGroup } from '@amplitude/analytics-node';

// set group with a single group name
setGroup('orgId', '15', {
  user_id: 'user@amplitude.com',
});

import { setGroup } from '@amplitude/analytics-node';

// set group with multiple group names
setGroup('sport', ['soccer', 'tennis'], {
  user_id: 'user@amplitude.com',
});

You can also set event-level groups by passing an Event Object with groups to track. With event-level groups, the group designation applies only to the specific event being logged, and doesn't persist on the user unless you explicitly set it with setGroup.

import { track } from '@amplitude/analytics-node';

track({
  event_type: 'event type',
  event_properties: { eventPropertyKey: 'event property value' },
  groups: { 'orgId': '15' }
}, undefined, {
  user_id: 'user@amplitude.com',
});

Group properties¶

Use the Group Identify API to set or update the properties of particular groups. These updates only affect events going forward.

The groupIdentify() method accepts a group type and group name string parameter, as well as an Identify object that's applied to the group.

import { Identify, groupIdentify } from '@amplitude/analytics-node';

const groupType = 'plan';
const groupName = 'enterprise';
const event = new Identify()
event.set('key1', 'value1');

groupIdentify(groupType, groupName, identify, {
  user_id: 'user@amplitude.com',
});

Revenue tracking¶

The preferred method of tracking revenue for a user is to use revenue() in conjunction with the provided Revenue interface. Revenue instances store each revenue transaction and allow you to define several special revenue properties (such as "revenueType", "productIdentifier", etc.) that are used in Amplitude's Event Segmentation and Revenue LTV charts. These Revenue instance objects are then passed into revenue() to send as revenue events to Amplitude. This lets automatically display data relevant to revenue in the platform. You can use this to track both in-app and non-in-app purchases.

To track revenue from a user, call revenue each time a user generates revenue. For example, a customer purchased 3 units of a product at $3.99.

import { Revenue, revenue } from '@amplitude/analytics-node';

const event = new Revenue()
  .setProductId('com.company.productId')
  .setPrice(3.99)
  .setQuantity(3);

revenue(event, {
  user_id: 'user@amplitude.com',
});

Revenue interface¶

Flush the event buffer¶

The flush method triggers the client to send buffered events.

import { flush } from '@amplitude/analytics-node';

flush();

By default, flush is called automatically in an interval, if you want to flush the events altogether, you can control the async flow with the optional Promise interface, for example:

await init(AMPLITUDE_API_KEY).promise;
track('Button Clicked', undefined, {
  user_id: 'user@amplitude.com',
});
await flush().promise;

Opt users out of tracking¶

You can turn off logging for a given user by setting setOptOut to true.

import { setOptOut } from '@amplitude/analytics-node';

setOptOut(true);

No events are saved or sent to the server while setOptOut is enabled, and the setting persists across page loads.

Re-enable logging by setting setOptOut to false.

import { setOptOut } from '@amplitude/analytics-node';

setOptOut(false);

Callback¶

All asynchronous APIs are optionally awaitable through a Promise interface. This also serves as a callback interface.

import { track } from '@amplitude/analytics-node';

// Using async/await
const results = await track('Button Clicked', undefined, {
  user_id: 'user@amplitude.com',
}).promise;
result.event; // {...} (The final event object sent to Amplitude)
result.code; // 200 (The HTTP response status code of the request.
result.message; // "Event tracked successfully" (The response message)

// Using promises
track('Button Clicked', undefined, {
  user_id: 'user@amplitude.com',
}).promise.then((result) => {
  result.event; // {...} (The final event object sent to Amplitude)
  result.code; // 200 (The HTTP response status code of the request.
  result.message; // "Event tracked successfully" (The response message)
});

Plugins¶

Plugins allow you to extend Amplitude SDK's behavior by, for example, modifying event properties (enrichment type) or sending to third-party APIs (destination type). A plugin is an object with methods setup() and execute().

add¶

The add method adds a plugin to Amplitude client instance. Plugins can help processing and sending events.

import { add } from '@amplitude/analytics-node';

add(new Plugin());

remove¶

The remove method removes the given plugin name from the client instance if it exists.

import { remove } from '@amplitude/analytics-node';

remove(plugin.name);

Create your custom plugin¶

Plugin.setup¶

This method contains logic for preparing the plugin for use and has config as a parameter. The expected return value is undefined. A typical use for this method, is to copy configuration from config or instantiate plugin dependencies. This method is called when the plugin is registered to the client via client.add().

Plugin.execute¶

This method contains the logic for processing events and has event as parameter. If used as enrichment type plugin, the expected return value is the modified/enriched event. If used as a destination type plugin, the expected return value is a map with keys: event (BaseEvent), code (number), and message (string). This method is called for each event instrumented using the client interface, including Identify, GroupIdentify and Revenue events.

Plugin examples¶

Enrichment type plugin¶

Here's an example of a plugin that modifies each instrumented event by adding an increment integer to event_id property of an event starting from 100.

import { init, add } from '@amplitude/analytics-node';
import { NodeConfig, EnrichmentPlugin, Event, PluginType } from '@amplitude/analytics-types';

export class AddEventIdPlugin implements EnrichmentPlugin {
  name = 'add-event-id';
  type = PluginType.ENRICHMENT as const;
  currentId = 100;
  config?: NodeConfig;

  /**
   * setup() is called on plugin installation
   * example: client.add(new AddEventIdPlugin());
   */
  async setup(config: NodeConfig): Promise<undefined> {
     this.config = config;
     return;
  }

  /**
   * execute() is called on each event instrumented
   * example: client.track('New Event');
   */
  async execute(event: Event): Promise<Event> {
    event.event_id = this.currentId++;
    return event;
  }
}

init('API_KEY');
add(new AddEventIdPlugin());

Destination type plugin¶

Here's an example of a plugin that sends each instrumented event to a target server URL using your preferred HTTP client.

import { init, add } from '@amplitude/analytics-node';
import { NodeConfig, DestinationPlugin, Event, PluginType, Result } from '@amplitude/analytics-types';
import fetch from 'node-fetch';

export class MyDestinationPlugin implements DestinationPlugin {
  name = 'my-destination-plugin';
  type = PluginType.DESTINATION as const;
  serverUrl: string;
  config?: NodeConfig;

  constructor(serverUrl: string) {
    this.serverUrl = serverUrl;
  }

  /**
   * setup() is called on plugin installation
   * example: client.add(new MyDestinationPlugin());
   */
  async setup(config: NodeConfig): Promise<undefined> {
    this.config = config;
    return;
  }

  /**
   * execute() is called on each event instrumented
   * example: client.track('New Event');
   */
  async execute(event: Event): Promise<Result> {
    const payload = { key: 'secret', data: event };
    const response = await fetch(this.serverUrl, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        Accept: '*/*',
      },
      body: JSON.stringify(payload),
    });
    return {
      code: response.status,
      event: event,
      message: response.statusText,
    };
  }
}

init('API_KEY');
add(new MyDestinationPlugin('https://custom.domain.com'));

Advanced topics¶

Custom HTTP Client¶

You can provide an implementation of Transport interface to the transportProvider configuration option for customization purpose, for example, sending requests to your proxy server with customized HTTP request headers.

import { Transport } from '@amplitude/analytics-types';

class MyTransport implements Transport {
  async send(serverUrl: string, payload: Payload): Promise<Response | null> {
    // check example: https://github.com/amplitude/Amplitude-TypeScript/blob/main/packages/analytics-client-common/src/transports/fetch.ts
  }
}

amplitude.init(API_KEY, {
  transportProvider: new MyTransport(),
});