> ## Documentation Index
> Fetch the complete documentation index at: https://launchdarkly-preview.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# JavaScript SDK observability reference

> This topic documents how to get started with the LaunchDarkly observability plugins for the client-side JavaScript SDK.

> For the complete documentation index, see [llms.txt](/llms.txt). For the full documentation snapshot, see [llms-full.txt](/llms-full.txt).

## Overview

This topic documents how to get started with the LaunchDarkly observability plugins for the client-side JavaScript SDK.

The JavaScript SDK supports the following observability plugins:

* An **Observability plugin** for error monitoring, logging, and tracing.
* A **Session replay plugin** that provides a way to record and replay end-user sessions from your application.

<Note title="SDK quick links">
  LaunchDarkly's SDKs are open source. In addition to this reference guide, we provide source, API reference documentation, and a sample application:
</Note>

| Resource | Location |
| - | - |
| SDK API documentation | [Observability plugin API docs](https://launchdarkly.github.io/observability-sdk/packages/@launchdarkly/observability/interfaces/api_observe.Observe.html) ,  [Session replay API docs](https://launchdarkly.github.io/observability-sdk/packages/@launchdarkly/observability/interfaces/api_record.Record.html) |
| GitHub repository | [@launchdarkly/observability](https://github.com/launchdarkly/observability-sdk/tree/main/sdk/%40launchdarkly/observability) |
| Published module | [npm](https://www.npmjs.com/package/@launchdarkly/observability) |

<Warning title="For use in client applications only">
  These observability and session replay plugins are for the LaunchDarkly client-side JavaScript-based SDKs.

  To learn more about LaunchDarkly's different SDK types, read [Choosing an SDK type](/sdk/concepts/client-side-server-side).
</Warning>

<Note title="The observability plugin replaces the JavaScript telemetry integration">
  We strongly recommend that any customers who are using LaunchDarkly's [browser-telemetry](https://github.com/launchdarkly/js-core/tree/main/packages/telemetry/browser-telemetry/) integration now use this observability plugin instead.

  As we develop additional telemetry-related functionality, we will only be adding it to this observability plugin.
</Note>

## Prerequisites and dependencies

This reference guide assumes that you are somewhat familiar with the LaunchDarkly [JavaScript SDK](/sdk/client-side/javascript).

The observability plugin is compatible with the [JavaScript SDK](/sdk/client-side/javascript), version 3.7.0 and later, and is automatically included in the JavaScript Browser SDK v1.

<Tip title="Do you need information about Angular, Remix, Svelte, or other frameworks?">
  LaunchDarkly does not offer SDKs for all languages or frameworks. If you're using another framework, such as Angular, Remix, or Svelte, you may be able to use the JavaScript SDK instead. Install the observability plugins and initialize them when you initialize the client for the JavaScript SDK.

  To request support for a specific language or framework, [start a Support ticket](https://support.launchdarkly.com/hc/en-us/requests/new).
</Tip>

## Get started

Follow these steps to get started:

* [Install the plugins](#install-the-plugins)
* [Initialize the JavaScript SDK client](#initialize-the-client)
* [Configure the plugin options](#configure-the-plugin-options)
* [Explore supported features](#explore-supported-features)
* [Review observability data in LaunchDarkly](#review-observability-data-in-launchdarkly)

## Install the plugins

LaunchDarkly uses plugins to the JavaScript SDK to provide observability. Most customers use both the observability and session replay plugins. However, there is no dependency between them, and you can use only one or the other if you like.

The first step is to make both the SDK and the observability plugins available as dependencies.

If you are using JavaScript Browser SDK v1, then the SDK, the observability plugin, and the session replay plugin are all in one package. If you are using an older version of the JavaScript SDK, or if you do not want to include both the observability plugin and the session replay plugin in your application, you can install the plugins separately by following the examples for the JavaScript SDK, v4.x.

Here's how:

<CodeGroup>
  ```bash title="npm, JS Browser SDK v1" theme={null}
  npm install @launchdarkly/browser
  ```

  ```bash title="yarn, JS Browser SDK v1" theme={null}
  yarn add @launchdarkly/browser
  ```

  ```bash title="npm, JS SDK v4.x" theme={null}
  npm install @launchdarkly/js-client-sdk
  npm install @launchdarkly/observability
  npm install @launchdarkly/session-replay
  ```

  ```bash title="yarn, JS SDK v4.x" theme={null}
  yarn add @launchdarkly/js-client-sdk
  yarn add @launchdarkly/observability
  yarn add @launchdarkly/session-replay
  ```

  ```bash title="npm, JS SDK v3.7+" theme={null}
  npm install launchdarkly-js-client-sdk
  npm install @launchdarkly/observability
  npm install @launchdarkly/session-replay
  ```

  ```bash title="yarn, JS SDK v3.7+" theme={null}
  yarn add launchdarkly-js-client-sdk
  yarn add @launchdarkly/observability
  yarn add @launchdarkly/session-replay
  ```
</CodeGroup>

Then, import the plugin into your code:

<CodeGroup>
  ```js title="Import, JS Browser SDK v1" theme={null}
  import { initialize } from "@launchdarkly/browser";
  ```

  ```js title="Import, JS SDK v4.x" theme={null}
  import { initialize } from "@launchdarkly/js-client-sdk";
  import Observability, { LDObserve } from "@launchdarkly/observability";
  import SessionReplay, { LDRecord } from "@launchdarkly/session-replay";
  ```

  ```js title="Import, JS SDK v3.7+" theme={null}
  import { initialize } from "launchdarkly-js-client-sdk";
  import Observability, { LDObserve } from "@launchdarkly/observability";
  import SessionReplay, { LDRecord } from "@launchdarkly/session-replay";
  ```
</CodeGroup>

## Initialize the client

Next, initialize the SDK and the plugins.

To initialize, you need your LaunchDarkly environment's client-side ID and, in some versions, the context for which you want to evaluate flags. This authorizes your application to connect to a particular environment within LaunchDarkly. To learn more, read [Initialize the client](/sdk/client-side/javascript#initialize-the-client) in the JavaScript SDK reference guide.

<Warning title="JavaScript observability SDK credentials">
  The JavaScript observability SDK requires a client-side ID. Client-side IDs are specific to each project and environment. They are not secret, and you can include them in client-side code. Do not embed a server-side SDK key in a client-side application.

  You can find client-side IDs and project keys in **Project settings**, on the **Environments** list. To learn more about key types, read [Keys](/sdk/concepts/client-side-server-side#keys).
</Warning>

You can initialize the observability plugins either at the same time you initialize the SDK, or afterwards.

### Initialize SDK client and plugins together

Here's how to initialize the SDK and plugins:

<Feature flag="docs-enable-browser-sdk-pkg" fallback={false} match={true}>
  <CodeGroup>
    ```js title="Initialize, JS Browser SDK v1" theme={null}
          const client = initialize('example-client-side-id', {
            observability: { /* observability plugin options here */ },
            sessionReplay: { /* session replay plugin options here */ }
          });
    ```

    ```js title="Initialize, JS SDK v4.x" theme={null}
          const client = initialize('example-client-side-id', {
            plugins: [ new Observability(), new SessionReplay() ]
          });
    ```

    ```js title="Initialize, JS SDK v3.7+" theme={null}
          // You'll need this context later, but you can ignore it for now.
          const context = {
            kind: 'user',
            key: 'example-context-key'
          };

          const client = initialize('example-client-side-id', context, {
            plugins: [ new Observability(), new SessionReplay() ]
          });
    ```
  </CodeGroup>
</Feature>

<Feature flag="docs-enable-browser-sdk-pkg" fallback={false} match={false}>
  <CodeGroup>
    ```js title="Initialize, JS SDK v4.x" theme={null}
          const client = initialize('example-client-side-id', {
            plugins: [ new Observability(), new SessionReplay() ]
          });
    ```

    ```js title="Initialize, JS SDK v3.7+" theme={null}
          // You'll need this context later, but you can ignore it for now.
          const context = {
            kind: 'user',
            key: 'example-context-key'
          };

          const client = initialize('example-client-side-id', context, {
            plugins: [ new Observability(), new SessionReplay() ]
          });
    ```
  </CodeGroup>
</Feature>

### Initialize the plugins after the SDK client

You can initialize the observability and session replay plugins manually, after the SDK client is initialized.

This approach supports feature-flagged rollouts or dynamic initialization after end user consent. Both plugins use a `manualStart` option combined with `.start()` calls.

First, configure the plugins with `manualStart: true`:

<Feature flag="docs-enable-browser-sdk-pkg" fallback={false} match={true}>
  <CodeGroup>
    ```js title="Manual start configuration, JS Browser SDK v1" theme={null}
          const client = initialize('example-client-side-id', {
            observability: {
              manualStart: true
              /* other observability plugin options here */
            },
            sessionReplay: {
              manualStart: true
              /* other session replay plugin options here */
            }
          });
    ```

    ```js title="Manual start configuration, JS SDK v4.x" theme={null}
          const client = initialize('example-client-side-id', {
            plugins: [
              new Observability({ manualStart: true }),
              new SessionReplay({ manualStart: true })
            ]
          });
    ```

    ```js title="Manual start configuration, JS SDK v3.7+" theme={null}
          // You'll need this context later, but you can ignore it for now.
          const context = {
            kind: 'user',
            key: 'example-context-key'
          };

          const client = initialize('example-client-side-id', context, {
            plugins: [
              new Observability({ manualStart: true }),
              new SessionReplay({ manualStart: true })
            ]
          });
    ```
  </CodeGroup>
</Feature>

<Feature flag="docs-enable-browser-sdk-pkg" fallback={false} match={false}>
  <CodeGroup>
    ```js title="Manual start configuration, JS SDK v4.x" theme={null}
          const client = initialize('example-client-side-id', {
            plugins: [
              new Observability({ manualStart: true }),
              new SessionReplay({ manualStart: true })
            ]
          });
    ```

    ```js title="Manual start configuration, JS SDK v3.7+" theme={null}
          // You'll need this context later, but you can ignore it for now.
          const context = {
            kind: 'user',
            key: 'example-context-key'
          };

          const client = initialize('example-client-side-id', context, {
            plugins: [
              new Observability({ manualStart: true }),
              new SessionReplay({ manualStart: true })
            ]
          });
    ```
  </CodeGroup>
</Feature>

Then, start the plugins when appropriate, such as after receiving end user consent or when a feature flag enables observability.

Here's an example starting the observability plugin:

<CodeGroup>
  ```js title="Start observability plugin" theme={null}
      // Start observability after user consent or feature flag check
      if (userConsentReceived || featureFlagEnabled) {
        LDObserve.start();
      }
  ```

  ```js title="Start observability with feature flag" theme={null}
      // Example: Start observability based on a feature flag
      const observabilityEnabled = client.variation('enable-observability', false);
      if (observabilityEnabled) {
        LDObserve.start();
      }
  ```

  ```js title="Start observability after end user action" theme={null}
      // Example: Start observability after user accepts analytics
      const handleAcceptAnalytics = () => {
        // Store user preference
        localStorage.setItem('analyticsAccepted', 'true');

        // Start observability
        LDObserve.start();
      };
  ```
</CodeGroup>

Here's an example with the session replay plugin:

<CodeGroup>
  ```js title="Start recording" theme={null}
      LDRecord.start({
        silent: false // if true, console.warn messages created in this method are skipped
      });
  ```

  ```js title="Stop recording" theme={null}
      LDRecord.stop();
  ```
</CodeGroup>

This approach allows you to:

* Feature-flag the rollout of observability to a subset of end users
* Wait for end user consent before starting data collection
* Dynamically enable observability based on runtime conditions
* Maintain compliance with privacy regulations

## Configure the plugin options

You can configure options for the observability plugins when you initialize the SDK. The plugin constructors take an optional object with the configuration details.

<Note title="Session replays are obscured by default">
  By default, session replays use the `strict` privacy setting, which obscures some data. Use <code>none</code> to turn off session replay obfuscation. This enables more detail on session replays, but may expose more of your customer data than your privacy or data retention policies allow. To learn more, read [Session replay config](/sdk/features/session-replay-config).
</Note>

Here is an example:

<Feature flag="docs-enable-browser-sdk-pkg" fallback={false} match={true}>
  <CodeGroup>
    ```js title="Plugin options, JS Browser SDK v1" theme={null}
          const client = initialize('example-client-side-id', {
            observability: {
              tracingOrigins: true, // attribute frontend requests to backend domains
              networkRecording: {
                enabled: true,
                recordHeadersAndBody: true
              }
            },
            sessionReplay: {
              privacySetting: 'strict',
                // or 'default' to redact text matching common regex for PII
                // or 'none' to turn off obfuscation
            }
          });
    ```

    ```js title="Plugin options, JS SDK v4.x" theme={null}
          const client = initialize('example-client-side-id', {
            plugins: [
              new Observability({
                tracingOrigins: true, // attribute frontend requests to backend domains
                networkRecording: {
                  enabled: true,
                  recordHeadersAndBody: true
                }
              }),
              new SessionReplay({
                // Use 'none' to turn off session replay obfuscation.  /sdk/features/session-replay-config
                privacySetting: 'strict',
                  // or 'default' to redact text matching common regex for PII
                  // or 'none' to turn off obfuscation
              })
            ]
          });
    ```

    ```js title="Plugin options, JS SDK v3.7+" theme={null}
          // You'll need this context later, but you can ignore it for now.
          const context = {
            kind: 'user',
            key: 'example-context-key'
          };

          const client = initialize('example-client-side-id', context, {
            plugins: [
              new Observability({
                tracingOrigins: true, // attribute frontend requests to backend domains
                networkRecording: {
                  enabled: true,
                  recordHeadersAndBody: true
                }
              }),
              new SessionReplay({
                privacySetting: 'strict',
                  // or 'default' to redact text matching common regex for PII
                  // or 'none' to turn off obfuscation
              })
            ]
          });
    ```
  </CodeGroup>
</Feature>

<Feature flag="docs-enable-browser-sdk-pkg" fallback={false} match={false}>
  <CodeGroup>
    ```js title="Plugin options, JS SDK v4.x" theme={null}
          const client = initialize('example-client-side-id', {
            plugins: [
              new Observability({
                tracingOrigins: true, // attribute frontend requests to backend domains
                networkRecording: {
                  enabled: true,
                  recordHeadersAndBody: true
                }
              }),
              new SessionReplay({
                privacySetting: 'strict',
                // or 'default' to redact text matching common regex for PII
                // or 'none' to turn off obfuscation
              })
            ]
          });
    ```

    ```js title="Plugin options, JS SDK v3.7+" theme={null}
          // You'll need this context later, but you can ignore it for now.
          const context = {
            kind: 'user',
            key: 'example-context-key'
          };

          const client = initialize('example-client-side-id', context, {
            plugins: [
              new Observability({
                tracingOrigins: true, // attribute frontend requests to backend domains
                networkRecording: {
                  enabled: true,
                  recordHeadersAndBody: true
                }
              }),
              new SessionReplay({
                privacySetting: 'strict',
                // or 'default' to redact text matching common regex for PII
                // or 'none' to turn off obfuscation
              })
            ]
          });
    ```
  </CodeGroup>
</Feature>

For more information on plugin options, read [Configuration for client-side observability](/sdk/features/observability-config-client-side) and [Configuration for session replay](/sdk/features/session-replay-config).

## Set Context-Security-Policy (CSP)

If your application runs in an environment that enforces content security policies, you must set the `Content-Security-Policy` (CSP) in your application to tell the browser how your page can interact with third-party scripts.

Here are the policies you need to set to use the observability plugin:

* `connect-src: https://pub.observability.app.launchdarkly.com https://otel.observability.app.launchdarkly.com`: This policy allows connecting with LaunchDarkly servers to send recorded observability data.
* `worker-src: data: blob:`: This policy allows creating an inline web worker initialized by the `npm` package for this plugin.

Your CSP definition may look something like this:

<CodeGroup>
  ```html title="Example CSP definition" theme={null}
      <meta
        http-equiv="Content-Security-Policy"
        content="connect-src: https://pub.observability.app.launchdarkly.com https://otel.observability.app.launchdarkly.com; worker-src data: blob:;"
      />

  ```
</CodeGroup>

Alternatively, you can set the CSP in the HTML document response header `Content-Security-Policy`. Check your initial app HTML document load for the header to make sure you are setting it to the desired value.

## Explore supported features

The observability plugin supports the following features. After the SDK and plugins are initialized, you can access these from within your application:

* [Configuration for client-side observability](/sdk/features/observability-config-client-side)
* [Configuration for session replay](/sdk/features/session-replay-config#javascript)
* [Errors](/sdk/features/observability-errors#javascript)
* [Logs](/sdk/features/observability-logs#javascript)
* [Metrics](/sdk/features/observability-metrics#javascript)
* [Tracing](/sdk/features/observability-traces#javascript)

## Review observability data in LaunchDarkly

After you initialize the SDK and observability plugins, your application automatically starts sending observability data back to LaunchDarkly in the form of custom events. You can review this information in the LaunchDarkly user interface. To learn how, read [Observability](/home/observability).

Specifically, the observability data includes events that LaunchDarkly uses to automatically create the following metrics:

* Average, P95, and P99 Cumulative Layout Shift (CLS) per context (LaunchDarkly)
* Average, P95, and P99 Document Load Latency per context (LaunchDarkly)
* Percentage of users with errors (LaunchDarkly)
* Average, P95, and P99 First Contentful Paint (FCP) per context (LaunchDarkly)
* Average, P95, and P99 First Input Delay (FID) per context (LaunchDarkly)
* Average, P95, and P99 Interaction to Next Paint (INP) per context (LaunchDarkly)
* Average, P95, and P99 Largest Contentful Paint (LCP) (LaunchDarkly)
* Average, P95, and P99 Time to First Byte (TTFB) per context (LaunchDarkly)

To learn more, read [Metrics autogenerated from observability events](/home/metrics/autogen/observability).