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React Client SDK

Getting Started​

The following will outline how to get up and running with Statsig for React.

Create an Account​

To work with the SDK, you will need a Statsig account. If you don't yet have an account, go ahead and sign up for a free account now.

You could skip this for now, but you will need an SDK key and some gates/experiments to use with the SDK in just a minute.

Installation​

You can install the Statsig React SDK via npm or yarn.

npm install statsig-react

Initialize the SDK​

After installation, you will need to initialize the SDK using a Client SDK key from the "API Keys" tab on the Statsig console.

These Client SDK Keys are intended to be embedded in client side applications. If need be, you can invalidate or create new SDK Keys for other applications/SDK integrations.

info

Do NOT embed your Server Secret Key in client side applications

In addition to the SDK key, you should also pass in a StatsigUser for feature gate targeting and experimentation grouping purposes.

The 3rd parameter is optional and allows you to pass in a StatsigOptions to customize the SDK.

At the root of your component tree, wrap your app in a StatsigProvider and set waitForInitialization=true.

import { StatsigProvider } from "statsig-react";

function App() {
  return (
    <StatsigProvider
      sdkKey="<STATSIG_CLIENT_SDK_KEY>"
      waitForInitialization={true}
      // StatsigOptions (Not Required)
      options={{
        environment: { tier: "staging" },
      }}
    >
      <div className="App">{/* Rest of App ... */}</div>
    </StatsigProvider>
  );
}
note

If you do not use waitForInitialization, all checks to Statsig will return default values until initialization completes.

Working with the SDK​

Checking a Gate​

Now that your SDK is initialized, let's check a Feature Gate. Feature Gates can be used to create logic branches in code that can be rolled out to different users from the Statsig Console. Gates are always CLOSED or OFF (think return false;) by default.

import { useGate } from "statsig-react";

...

function MyComponent() {
  const { value, isLoading } = useGate("a_gate_name");

  // Only required if you have not set waitForInitialization to true
  if (isLoading) {
    return <div>Fetching Values...</div>;
  }

  return <div>{value ? "Passes Gate" : "Fails Gate"}</div>;
}

Reading a Dynamic Config​

Feature Gates can be very useful for simple on/off switches, with optional but advanced user targeting. However, if you want to be able send a different set of values (strings, numbers, and etc.) to your clients based on specific user attributes, e.g. country, Dynamic Configs can help you with that. The API is very similar to Feature Gates, but you get an entire json object you can configure on the server and you can fetch typed parameters from it. For example:

import { useConfig } from "statsig-react";

...
function MyComponent() {
  const { config, isLoading } = useConfig("a_config_name");

  // Only required if you have not set waitForInitialization to true
  if (isLoading) {
    return <div>Fetching Values...</div>;
  }

  return <div>{config.get("header_label", "Welcome")}</div>;
}

Getting an Layer/Experiment​

Then we have Layers/Experiments, which you can use to run A/B/n experiments. We offer two APIs, but we recommend the use of layers to enable quicker iterations with parameter reuse.

import { useLayer } from "statsig-react";

...
function MyComponent() {
  const { layer, isLoading } = useLayer("a_layer");

  // Only required if you have not set waitForInitialization to true
  if (isLoading) {
    return <div>Fetching Values...</div>;
  }

  return (
    <div>
      <h1>{layer.get("title", "Welcome to Statsig!")}</h1>
      <p>{layer.get("discount", 0.1)}</p>
    </div>
  );
}

Logging an Event​

Now that you have a Feature Gate or an Experiment set up, you may want to track some custom events and see how your new features or different experiment groups affect these events. This is super easy with Statsig - simply call the Log Event API for the event, and you can additionally provide some value and/or an object of metadata to be logged together with the event:

import { Statsig } from "statsig-react";

Statsig.logEvent("add_to_cart", "SKU_12345", {
  price: "9.99",
  item_name: "diet_coke_48_pack",
});

// or via a React Hook

import { useStatsigLogEffect } from "statsig-react";

function MyComponent() {
  useStatsigLogEffect("my_custom_event", "SKU_12345", {
    price: "9.99",
    item_name: "diet_coke_48_pack",
  });

  return <div>...</div>;
}

Statsig User​

You should provide a StatsigUser object whenever possible when initializing the SDK, passing as much information as possible in order to take advantage of advanced gate and config conditions (like country or OS/browser level checks).

Most of the time, the userID field is needed in order to provide a consistent experience for a given user (see logged-out experiments to understand how to correctly run experiments for logged-out users).

If the user is logged out at the SDK init time, you can leave the `userID` out for now, and we will use a stable device ID that we create and store in the local storage for targeting purposes.

Besides userID, we also have email, ip, userAgent, country, locale and appVersion as top-level fields on StatsigUser. In addition, you can pass any key-value pairs in an object/dictionary to the custom field and be able to create targeting based on them.

const [user, setUser] = useState({
  userID: "a-user",
  email: "user-a@gmail.com"
});

...

// Pass your StatsigUser into the StatsigProvider
return (
    <StatsigProvider
      sdkKey="client-key"
      waitForInitialization={true}
      user={user}
    >

Private Attributes​

Have sensitive user PII data that should not be logged? No problem, we have a solution for it! On the StatsigUser object we also have a field called privateAttributes, which is a simple object/dictionary that you can use to set private user attributes. Any attribute set in privateAttributes will only be used for evaluation/targeting, and removed from any logs before they are sent to Statsig server.

For example, if you have feature gates that should only pass for users with emails ending in "@statsig.com", but do not want to log your users' email addresses to Statsig, you can simply add the key-value pair { email: "my_user@statsig.com" } to privateAttributes on the user and that's it!

Updating the StatsigUser​

If/when the user object changes, the SDK will automatically fetch the updated values for the new user object - if waitForInitialization is false, and no mountKey is set on the StatsigProvider, this will trigger a re-render for the new user with default values, followed by a render when the values have been updated.

const [user, setUser] = useState({userID: 'initial-user'});

return (
  <StatsigProvider
    sdkKey="CLIENT_KEY_HERE"
    waitForInitialization={false}
    user={user}
  >
    <GateTwo />
  </StatsigProvider>
);

// Some time later
setUser({ userID: "another-user" });

If you do not want to pass your setUser function down to the component that needs to update the user, you can use the provided useUpdateUser hook to pull it off of the StatsigContext.

const [user, setUser] = useState({userID: 'initial-user'});

return (
  <StatsigProvider
    sdkKey="CLIENT_KEY_HERE"
    waitForInitialization={false}
    user={user}
    setUser={setUser} // <-- This is required for the hook to work
  >
    <GateTwo />
  </StatsigProvider>
);

// Some time later
import { useUpdateUser } from "statsig-react";

const updateUser = useUpdateUser(); // <-- This retrieves the same setUser function given to the StatsigProvider
updateUser({ userID: "another-user" });

There's also an updateUser method on the Statsig interface, but calling this directly may lead to issues with the StatsigProvider.

Fetch Mode v1.26.0+​

In some advanced use cases, you may want to limit the number of network requests to be fired during updates to the current user.

Since version 1.26.0, the React SDK supports StatsigOptions.fetchMode. Setting this option will change the bevahior of Statsig.updateUser.

The supported FetchModes are as follows:

  • network-only - This is the default behavior. The SDK will always fetch the latest feature gate and experiment values from the Statsig servers when Statsig.updateUser is called.

  • cache-or-network - When set to this mode, the SDK will first check if a cached value exists for the user and was cached during this session (After Statsig.initialize). If no valid cache value is found, a network request will be made to fetch the latest values.

Server Side Rendering​

Starting in v1.9.1, the react SDK supports server side rendering via the StatsigSynchronousProvider. This provider takes in similar properties to the StatsigProvider with a few exceptions:

  • the addition of an initializeValues prop, which takes in the initializeValues generated by a Statsig Server SDK that supports Client SDK Bootstrapping. Normally, client SDKs fetch this value by hitting the /initialize endpoint

  • consequently, there is no waitForInitialization or initializingComponent as the SDK is initialized and has all of the values immediately when rendered on the server (or on the first render pass on the client).

Note that if the user object changes, the provider will update the user and values via a call to Statsig servers.

danger

Pick a single provider to wrap your app - don't return the StatsigSynchronousProvider when executing on the server, and swap it out with the StatsigProvider when rendered on the client (or vice versa). Pick one provider for your use case and only render that

Manual Exposures v1.21.0+​

danger

Manually logging exposures can be tricky and may lead to an imbalance in exposure events. For example, only triggering exposures for users in the Test group of an experiment will imbalance the experiment, making it useless.

Added in version 1.21.0, you can now query your gates/experiments without triggering an exposure as well as manually logging your exposures.

To check a gate without an exposure being logged, call the following.

const { value } = useGateWithExposureLoggingDisabled("a_gate_name");

Later, if you would like to expose this gate, you can call the following.

Statsig.manuallyLogGateExposure("a_gate_name");

Testing​

At Statsig, we use this jest mock to test our components:

let mockGates: Record<string, boolean> = {};
let mockLayers: Record<string, Layer> = {};
jest.mock('statsig-react', () => {
  const DynamicConfig = jest.requireActual('statsig-react')
    .DynamicConfig as new (mockName: string) => DynamicConfig;
  const StatsigMock = {
    useGate: (gateName: string) => {
      return {
        isLoading: false,
        value: mockGates[gateName] ?? false,
      };
    },
    useConfig: () => {
      return {};
    },
    useLayer: (name: string) => {
      return { layer: mockLayers[name], isLoading: false };
    },
    useExperiment: (name: string) => {
      return {
        isLoading: false,
        config: new DynamicConfig(name),
      };
    },
    StatsigProvider: (props: object) => {
        return <>
            props.children
        </>
    },
    Statsig: {
      logEvent: () => {},
      checkGate: (gateName: string) => mockGates[gateName] ?? false,
      getConfig: () => {
        return {
          get: (name: string, fallback: any) => fallback,
          getValue: (name: string, fallback: any) => fallback,
        };
      },
      getLayer: (layerName: string) => {
        return StatsigMock.Layer._create(layerName);
      },
    },

    Layer: {
      _create(
        _layerName: string,
        _layerValue: Record<string, any> = {},
        _ruleID = '',
        _secondaryExposures: Record<string, string>[] = [],
        _allocatedExperimentName = '',
      ) {
        return {
          get: function <T>(
            _key: string,
            defaultValue: T,
            _typeGuard?: (value: unknown) => value is T,
          ): T {
            return defaultValue;
          },
        };
      },
    },
  };
  return StatsigMock;
});

If you want to use local overrides, you can create a helper function to make this easier:

import { Statsig, StatsigContext, StatsigProvider } from 'statsig-react'

function StatsigOverrides({children}) {
    const statsigContext = useContext(StatsigContext);
    useEffect(() => {
      // make sure you import this from statsig-react!
      Statsig.overrideConfig("a_config", {test_key: "test_value"});
    }, [statsigContext.initialized]);
       
    return statsigContext.initialized ? children : null;
}

<StatsigProvider ...>
  <StatsigOverrides>
    <App />
  </StatsigOverrides>
</StatsigProvider>

FAQ​

How do I run experiments for logged out users?​

See the guide on device level experiments

Which Browsers Supported?​

The statsig-react SDK relies on the statsig-js SDK and inherits its browser compatibility. For more information, see the statsig-js docs.

How do I silence "Call and wait for initialize() to finish first" logs?​

Starting in v1.6.0, setting the environment variable REACT_APP_STATSIG_SDK_MODE=silent will swallow the Call and wait for initialize() to finish first exception. For more information, see the release notes for v1.6.0

Can I write my own StatsigProvider?​

If you wish to use the React SDK but customize the initialization logic beyond what the StatsigProvider offers, you can write your own provider. See the above warning on using the global Statsig singleton before proceeding.

An example provider with custom initialization logic might look something like this:

Reference​

Statsig​

You can import the global Statsig singleton to call SDK functions outside of a component tree or in callbacks/loops/or wherever else you are unable to use hooks. For all SDK functions, see the statsig-js sdk docs.

caution

If you are calling methods on the global Statsig like initialize or updateUser, the user object tracked by the provider and the user object used outside the component tree can get out of sync. You are responsible for maintaining the state of the user and keeping it consistent with the StatsigProvider in these cases. The statsig-react SDK uses the global Statsig class to serve gate/config/experiment checks, but these are memoized in the hooks the SDK provides. Updates to the user which impact flag values that are made outside the context of the react component tree will not be reflected in the component tree unless the updated user is passed in to the StatsigProvider.

StatsigProvider​

The StatsigProvider is a react context provider which initializes the SDK, and passes down its state to the rest of the react application via a StatsigContext. It takes the following properties:

  • children: React.ReactNode | React.ReactNode[] - One or more child components
  • sdkKey: string - A client SDK key from the Statsig Console
  • user: StatsigUser - A StatsigUser object. Changing this will update the experiment and gate values, causing a re-initialization and rerender
  • options?: StatsigOptions - See StatsigOptions. An optional bag of initialization properties (mostly shared with the statsig-js sdk) for advanced configuration.
  • waitForInitialization?: boolean -
  • initializingComponent?: React.ReactNode | React.ReactNode[] - A loading component to render if and only if waitForInitialization is set to true and the SDK is initializing
  • mountKey?: string - A key for stable mounting/unmounting when updating the user. If this key is set and changes when the user object changes (or if it is not provided) Then the children of StatsigProvider will unmount/remount with the async update. If this key is set and does not change, then the children of StatsigProvider will continue to be mounted, and it will trigger a rerender after updateUser completes.
  • shutdownOnUnmount?: boolean - If set to true, will automatically call Statsig.shutdown() when the provider is unmounted

StatsigSynchronousProvider​

The StatsigSynchronousProvider is a altered version of the StatsigProvider, made specifically for Server Side Rendering but can also be leveraged for apps that do not require loading states.

  • children: React.ReactNode | React.ReactNode[] - One or more child components
  • sdkKey: string - A client SDK key from the Statsig Console
  • user: StatsigUser - A StatsigUser object. Changing this will update the experiment and gate values, causing a re-initialization and rerender
  • options?: StatsigOptions - See StatsigOptions. An optional bag of initialization properties (mostly shared with the statsig-js sdk) for advanced configuration.
  • initializeValues: Record<string, unknown> - JSON object, generated by a Statsig Server SDK. See Server Side Rendering.

StatsigContext​

StatsigContext is a react context used internally by the SDK to manage internal state. You should not need to use the StatsigContext directly, as the Provider and Hooks interface with it for you. It tracks the following state:

  • initialized: boolean; the initialization state of the SDK
  • statsigPromise: React.MutableRefObject<Promise<void>> | null; a reference to a promise which resolves once SDK initialization is complete
  • initStarted: boolean whether the singleton Statsig has had initialize called on it, meaning the SDK is now usable and can serve checks from cache and queue log events
  • userVersion: number used interally by the SDK to memoize SDK functions based on the user. Increments when the user object is changed and updateUser is called.

StatsigOptions​

  • environment: StatsigEnvironment, default null
    • An object you can use to set environment variables that apply to all of your users in the same session and will be used for targeting purposes.
    • The most common usage is to set the environment tier ('production', 'staging' or 'development'), e.g. { tier: 'staging' }, and have feature gates pass/fail for specific environments.
  • disableCurrentPageLogging boolean, default false.
    • By default, the sdk appends the current page for log events to the event payload to generate user journey/funnel analytics
  • loggingIntervalMillis: number, default 5000 (5s), min 1000, max 60000
    • How frequently to flush logs to statsig (milliseconds)
  • loggingBufferMaxSize: number, default 10), min 2, max 500
    • Maximum number of events to buffer before flushing events to statsig
  • disableNetworkKeepalive: boolean, default false
    • Entirely disables the keepalive flag from being appended to network requests issued by the SDK
  • api - default https://api.statsig.com/v1/
    • The default endpoint to use for all SDK network requests. You should not override this (unless you have another API that implements the Statsig API endpoints)
    • If you wish to separately override the log_event endpoint only, see eventLoggingApi
  • overrideStableID - string, default null
    • If you'd like to use your own ID in place of Statsig's stableID, then you can pass the ID as an option here.
    • Once a value is passed, the SDK will store this ID in the local storage for the browser for future use as well.
  • localMode - boolean, default false
    • Pass true to this option to turn on Local Mode for the SDK, which will stop the SDK from issuing any network requests and make it only operate with only local overrides (If supported) and cache.
      Note: Since no network requests will be made, a dummy SDK key starting with "client-" can be used. (eg "client-key")
  • initTimeoutMs - number, default 3000
    • This option configures the maximum time (in milliseconds) the SDK would wait for the network request made by initialize() to respond before it resolves.
    • If the SDK resolves before the network request has completed due to the timeout, it will continue work with local overrides, cached values, and then default values set in code.
  • disableErrorLogging - boolean, default false
    • By default, the SDK auto logs javascript errors to Statsig. This will be connected with the metrics and pulse views to show the impact of new features on key error metrics
  • disableAutoMetricsLogging - boolean, default false
    • By default, the SDK auto logs javascript performance metrics to Statsig. This will be connected with the metrics and pulse views to show the impact of new features on key performance metrics
  • eventLoggingApi? string, default 'https://events.statsigapi.net/v1/
    • The SDK will hit different endpoints for initialize to evaluate gates and for logEvent to log event data. The api option controls the evaluation endpoint, and eventLoggingApi controls the event logging endpoint.
  • prefetchUsers? StatsigUser[] | null, default null
    • An array of additional StatsigUser objects to be fetched during the statsig.initialize call. A max of 5 users is enforced, if more than 5 users are provided, the 5 users at the start of the array will be used.
  • fetchMode? network-only | cache-or-network, default network-only
    • Changes the behavior of updateUser calls. See Fetch Mode for more details.
  • initCompletionCallback? (initDurationMs: number, success: boolean, message: string | null) => void, default null
    • A callback that's invoked whenever initialization has completed.
  • updateUserCompletionCallback? (durationMs: number, success: boolean, message: string | null) => void, default null
    • A callback that's invoked whenever an updateUser call has completed.

Hooks​

useGate​

A react hook to get a Statsig Feature Gate.

Parameters:

  • gateName: string - the name of the gate to check

Returns GateResult:

  • isLoading: boolean; - the loading/initializing state of the SDK
  • value: boolean - the value of the feature gate (false by default)

useConfig​

A react hook to get a Statsig Dynamic Config.

Parameters:

  • configName: string - the name of the config to get

Returns ConfigResult:

  • isLoading: boolean; - the loading/initializing state of the SDK
  • config: DynamicConfig - the backing DynamicConfig (see the statsig-js sdk docs for more information)

useExperiment​

A react hook to get a Statsig Experiment, represented as a DynamicConfig.

Parameters:

  • experimentName: string - the name of the experiment to get

Returns ConfigResult:

  • isLoading: boolean; - the loading/initializing state of the SDK
  • config: DynamicConfig - the backing DynamicConfig (see the statsig-js sdk docs for more information)

useLayer​

A react hook to get a Statsig Experiment, represented as a Layer.

Parameters:

  • experimentName: string - the name of the experiment to get

Returns LayerResult:

  • isLoading: boolean; - the loading/initializing state of the SDK
  • layer: Layer - the backing Layer (see the statsig-js sdk docs for more information)

useStatsigLogEffect​

A react hook to simplify top level logEvents into an effect which will only log and event once the SDK is ready

Parameters:

  • eventName: string
  • value?: string | number | null
  • metadata?: Record<string, string> | null

usePrefetchUsers (v1.15.0+)​

A react hook to prefetch an array of StatsigUser objects. This will call the underling prefetchUsers method.

Parameters:

  • users: StatsigUser[]