> For the complete documentation index, see [llms.txt](https://docs.sealights.io/knowledgebase/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.sealights.io/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent.md).

# Node.js Agent

Use the Node.js Agent to collect coverage and test data from JavaScript and TypeScript applications.

It supports:

* Frontend apps such as Angular, React, and Vue
* Backend Node.js services
* In-process test coverage uploads
* Out-of-process functional test coverage

{% hint style="info" %}
This page helps you choose the right setup. Use the stepper to pick the application path and test flow that match your use case.
{% endhint %}

{% stepper %}
{% step %}

### Start here

Follow these pages in order:

1. [Download the agent](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/downloading-the-node.js-agent.md)
2. [Generate a session ID](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/generating-a-session-id.md)
3. [Scan your application](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/scanning-your-application.md)

After the scan, choose your application path and test flow.

{% hint style="warning" %}
Do not choose the test flow until the scan is complete. Both in-process and out-of-process coverage depend on the scanned build map.
{% endhint %}
{% endstep %}

{% step %}

### Choose your application path

Choose the application path that matches your build and deployment model.

{% tabs %}
{% tab title="🌐 Frontend app" %}
Use this path for bundled browser apps.

* Scan the built output
* Instrument the files with `instrument` before deployment
* Run out-of-process functional tests against the instrumented app

Next pages:

* [Capturing Runtime Coverage](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/capturing-runtime-coverage.md)
* [Frontend Instrumentation (static)](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/capturing-runtime-coverage/frontend-instrumentation-static.md)
* [Capturing Tests](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/capturing-tests.md)
  {% endtab %}

{% tab title="🖥️ Backend service" %}
Use this path for Node.js APIs, workers, and server processes.

* Scan the service code
* Start the app with `run`
* Run out-of-process functional tests against the live service

Next pages:

* [Capturing Runtime Coverage](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/capturing-runtime-coverage.md)
* [Backend Instrumentation (dynamic)](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/capturing-runtime-coverage/backend-instrumentation-dynamic.md)
* [Capturing Tests](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/capturing-tests.md)
  {% endtab %}
  {% endtabs %}
  {% endstep %}

{% step %}

### Choose your test flow

Choose the test flow that matches how your tests run and where coverage comes from.

{% tabs %}
{% tab title="🧪 In-process tests (Unit Tests)" %}
Use this flow when the test runner executes the application code in the same process.

Typical examples:

* Unit tests
* In-process integration tests
* Mocha, Karma, or AVA runs that produce NYC coverage

How it works:

* Open a test stage
* Run the tests
* Upload JUnit results
* Upload the NYC coverage file with `nycReport`

{% hint style="info" %}
This flow uses the test runner output as the coverage source. It does not rely on a separately running application.
{% endhint %}

Framework pages:

* [Unit Tests](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/capturing-tests/unit-tests.md)
* [Mocha Tests framework](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/capturing-tests/mocha-tests-framework.md)
* [Karma Test Framework](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/capturing-tests/karma-test-framework.md)
* [AVA framework](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/capturing-tests/ava-framework.md)
  {% endtab %}

{% tab title="🔗 Out-of-process tests (Functional Tests)" %}
Use this flow when tests run against a separate application process.

Typical examples:

* Functional tests
* End-to-end tests
* Browser or API tests that target a running app

How it works:

* Scan the app
* Instrument the frontend build or start the backend with `run`
* Open a test stage for the external test runner
* Run the tests against the live app
* Upload JUnit results while the app reports footprints

{% hint style="warning" %}
This flow uses the running application as the coverage source. It usually relies on a **Lab ID** to connect the test runner with the instrumented app.
{% endhint %}

{% hint style="info" %}
Choose this flow for functional, API, browser, and end-to-end tests that target a live application.
{% endhint %}

Mocha can also be used here when it drives a separate running application. Other common frameworks include Playwright and similar functional test runners.

Next pages:

* [Capturing Runtime Coverage](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/capturing-runtime-coverage.md)
* [Capturing Tests](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/capturing-tests.md)
  {% endtab %}
  {% endtabs %}
  {% endstep %}
  {% endstepper %}

### Common next pages

* [Advanced Features](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/advanced-features.md)
* [Legacy Commands (Deprecated)](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/legacy-commands-deprecated.md)
* [Command Reference](/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/command-reference.md)


---

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