The [Ampli Wrapper](/docs/sdks/ampli#ampli-wrapper) is a generated, strongly typed API for tracking Analytics events based on your Tracking Plan in Amplitude Data. The tracking library exposes a function for every event in your team's tracking plan. The function's arguments correspond to the event's properties. [Ampli](/docs/sdks/ampli) can benefit your app by providing autocompletion for events and properties defined in Data and enforcing your event schemas in code to prevent bad instrumentation. {% callout type="tip" title="Enable real-time type checking for JavaScript" %} Because JavaScript isn't a type-safe language, static type checking isn't built in like TypeScript. Some common IDEs allow real-time type checks in JavaScript based on JSDoc. For a better development experience, Ampli generates JSDocs for all methods and classes. To enable real-time type checking in VSCode for JavaScript: 1. Go to *Preferences > Settings*, then search for **checkJs**. 2. Select *JS/TS > Implicit Project Config: Check JS*. After you activate the setting, type errors appear directly in the IDE. Jetbrains provides similar support: 1. Go to *Preferences > Editor > Inspections > JavaScript and TypeScript > General*. 2. In **Signature mismatch** and **Type mismatch**, set **Severity** to Warning or Error based on the strictness you want. {% /callout %} {% callout type="tip" title="Linting with Prettier" %} To prevent linting errors for eslint and tslint, the SDK-generated files have the following to disable the linters: `/* tslint:disable */` `/* eslint-disable */` There's no corresponding "in-code" functionality with Prettier. Instead, add the generated `path/to/ampli` to your `.prettierignore` file. You can get the path with `ampli pull`. Go to the [Prettier documentation](https://prettier.io/docs/en/ignore.html) for more information. {% /callout %} ## Quick start 1. [(Prerequisite) Create a Tracking Plan in Amplitude Data](/docs/data/create-tracking-plan). 2. [Install the Amplitude SDK](#install-the-amplitude-sdk). ```bash npm install @amplitude/node@^1.10.2 @amplitude/identify@^1.10.2 @amplitude/types@^1.10.2 ``` 3. [Install the Ampli CLI](#install-the-ampli-cli). ```bash npm install -g @amplitude/ampli ``` 4. [Pull the Ampli Wrapper into your project](#pull). ```bash ampli pull [--path ./src/ampli] ``` 5. [Initialize the Ampli Wrapper](#load). ```js import { ampli } from "./src/ampli"; ampli.load({ client: { apiKey: AMPLITUDE_API_KEY } }); ``` 6. [Identify users and set user properties](#identify). ```js ampli.identify("user-id", { userProp: "A trait associated with this user", }); ``` 7. [Track events with strongly typed methods and classes](#track). ```js ampli.songPlayed('ampli-user-id', { songId: 'song-1' }); ampli.track('ampli-user-id', new SongPlayed({ songId: 'song-2' }); ``` 8. [Flush events before application exit](#flush). ```js ampli.flush(); ``` 9. [Verify implementation status with CLI](#status). ```bash ampli status [--update] ``` ## Install the SDK If you haven't already, install the core Amplitude SDK dependencies. ```bash npm install @amplitude/node@^1.10.2 @amplitude/identify@^1.10.2 @amplitude/types@^1.10.2 ``` ## Install Ampli You can install the [Ampli CLI](/docs/sdks/ampli/ampli-cli) from Homebrew or NPM. {% code-group %} ```bash npm npm install -g @amplitude/ampli ``` ```bash brew brew tap amplitude/ampli brew install ampli ``` {% /code-group %} ## Pull the Ampli Wrapper into your project Run the Ampli CLI `pull` command from your project root to log in to Amplitude Data and download the strongly typed Ampli Wrapper for your tracking plan. ```bash ampli pull ``` The CLI prompts you to log in to your workspace and select a source. ```bash ➜ ampli pull Ampli project is not initialized. No existing `ampli.json` configuration found. ? Create a new Ampli project here? Yes ? Organization: Amplitude ? Workspace: My Workspace ? Source: My Source ``` ## Initialize Ampli Initialize Ampli in your code. {% code-group %} ```ts TypeScript import { ampli } from "./ampli"; ampli.load({ client: { apiKey: AMPLITUDE_API_KEY } }); ``` ```js JavaScript const { ampli } = require("./ampli"); ampli.load({ client: { apiKey: AMPLITUDE_API_KEY } }); ``` {% /code-group %} The `load()` function requires an options object to configure the SDK's behavior: | Option | Type | Required | Description | | ----------------- | ------------------- | --------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `disabled` | `Boolean` | optional | Specifies whether the Ampli Wrapper does any work. When `true`, all calls to the Ampli Wrapper are no-ops. Useful in local or development environments. Defaults to `false`. | | `client.instance` | `AmplitudeClient` | required if `client.apiKey` isn't set | Specifies an Amplitude instance. By default Ampli creates an instance for you. | | `client.apiKey` | `String` | required if `client.instance` isn't set | Specifies an API Key. This option overrides the default, which is the API Key configured in your tracking plan. | | `client.options` | `Amplitude.Options` | optional | Overrides the default configuration for the AmplitudeClient. | ## Identify Call `identify()` to set user properties. Ampli creates types for user properties, just as it does for events and event properties. The `identify()` function accepts an optional `userId`, optional user `properties`, and optional `options`. For example, your tracking plan contains a user property called `role`. The property's type is a string. ```js ampli.identify("user-id", { role: "Admin", }); ``` The options argument lets you pass [Amplitude fields](/docs/apis/analytics/http-v2#event-array-keys) for this call, such as `deviceId`. ```js ampli.identify( "user-id", { role: "admin", }, { deviceId: "my-device-id", }, ); ``` ## Group Call `setGroup()` to associate a user with their group (for example, their department or company). The `setGroup()` function accepts a required `groupType` and `groupName`. ```js ampli.setGroup("user-id", "Group name", "Group Value"); ``` 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 performs the specific event, 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` is '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 for that user's `groupType`. `groupType` is a string. `groupName` can be a string or an array of strings to indicate that a user is in multiple groups. {% callout type="example" heading="" %} For example, if Joe is in 'orgId' '10' and '20', the `groupName` is '[10, 20]'. Your code might look like this: ```js ampli.setGroup("user-id", "orgId", ["10", "20"]); ``` {% /callout %} ## Track To track an event, call the event's corresponding function. Every event in your tracking plan gets its own function in the Ampli Wrapper. The call uses this structure: ```js ampli.eventName( userId: string | undefined, properties: EventProperties, options: EventOptions, extra: MiddlewareExtra ) ``` `userId`: in multi-tenant, server environments, you must provide a `userId` for each tracking call to associate the event with a user. `properties`: passes event properties specific to this event in the tracking plan. The `options` argument lets you pass [Amplitude fields](/docs/apis/analytics/http-v2#event-array-keys), like `price`, `quantity`, and `revenue`. The `extra` argument lets you pass data to middleware. For example, your tracking plan contains an event called Song Played. The SDK generates the `songPlayed` function for the event, using camel case to make the name valid JavaScript. The event has two required properties: `songId` and `songFavorited`. The property type for `songId` is string, and `songFavorited` is a boolean. The event has two Amplitude fields: `price` and `quantity`. Learn more about [Amplitude fields](/docs/apis/analytics/http-v2#event-array-keys). The event has one MiddlewareExtra: `myMiddleware`. Learn more about [middleware](/docs/sdks/sdk-middleware). ```js ampli.songPlayed( "ampli-user-id", { songId: "songId", // string, songFavorited: true, // boolean }, { price: 1.23, quantity: 2, }, { myMiddleware: { myMiddlewareProp: "value to send to middleware" }, }, ); ``` Ampli also generates a class for each event. ```js const myEventObject = new SongPlayed({ songId: "songId", // string, songFavorited: true, // boolean }); ``` Track Event objects using Ampli `track`: ```js ampli.track( "ampli-user-id", new SongPlayed({ songId: "songId", // string, songFavorited: true, // boolean }), ); ``` ## Flush The Ampli Wrapper queues events and sends them on an interval based on the configuration. Ampli flushes the buffer automatically when `flushQueueSize` or `flushInterval` reach their thresholds, so you don't need to call `flush()` for normal operation. Call `flush()` to immediately send any pending events. The `flush()` method returns a promise that you can use to ensure Ampli sends all pending events before continuing. This is useful before the application exits. ```js ampli.flush(); ``` ## Status Verify that your code implements all tracked events with the `status` command: ```bash ampli status [--update] ``` The output displays status and indicates what events are missing. ```bash ➜ ampli status ✘ Verifying event tracking implementation in source code ✔ Song Played (1 location) ✘ Song Stopped Called when a user stops playing a song. Events Tracked: 1 missed, 2 total ```