# Node.js SDK with ESM

## 1.  Installing node-SDK package

```bash
npm install @hypertestco/node-sdk --save-exact 
```

## 2.  Initializing sdk

####  2.1 Adding SDK in code and Initialize open telemetry sdk with hypertest

* ***Create a new file*** and add this code to initialize hypertest node sdk, then import that file at the top of your entryfile.

{% hint style="warning" %}
It is necessary to initialize sdk in a separate file and then import that file at the top of your entry file. This is needed with esm because imports are loaded before the file's code is run.
{% endhint %}

{% hint style="warning" %}
Hypertest sdk needs to be initialized as early as possible. Make sure no require/import call is made before that.
{% endhint %}

```typescript
// import * as htSdk from '@hypertestco/node-sdk'; // for esm/ts
const htSdk = require('@hypertestco/node-sdk'); // for commonJS
htSdk.initialize({
    apiKey: '<your-api-key>',
    serviceId: '<your-service-identifier-from-dashboard>',
    serviceName: '<organizationName:service-name>',
    exporterUrl: '<hypertest-logger-url>',
    // ignoredHostsForHttpReqs: ['abc.xyz.com', /^\d+\.abcd\.co(m|)$/],
    // disableInstrumentations: [] // htSdk.HtInstrumentations enum. 
});
```

#### 2.2 Mark app as ready

Call the markAppAsReady method when the app is ready to receive traffic, it indicates that tests can be started (This is important ONLY FOR REPLAY mode).

<pre class="language-javascript"><code class="lang-javascript">// Rest Application code...
// add htSdk.markAppAsReady(); when your app is ready to accept requests
<strong>app.listen(3000, () => {
</strong><strong>  console.log(`Listening for requests on http://localhost:3000`);
</strong>  // Indicates the App has booted up successfully for REPLAY And Tests can be started
  htSdk.markAppAsReady();
});
</code></pre>

#### 2.3 Use hypertest esm hooks

Give hypertest's esm hooks to the node's esm hooks loader API. This will happen where you start your app with node

```bash
HT_MODE=RECORD node --loader=@hypertestco/node-sdk/hooks.mjs my-app.js
```

{% hint style="warning" %}
*ts-node* or *tsx* can't be used to run your project. Your source code needs to be transpiled to js and then run using node.
{% endhint %}

To enable hypertest, set the `HT_MODE` env variable to `RECORD` and start your app

{% hint style="warning" %}
HT\_MODE can't be set at the top of your entryfile like this.

```javascript
// DO NOT DO THIS AT ALL FOR ESM !!!
process.env.HT_MODE = process.env.HT_MODE || 'RECORD';
```

It only works with cjs because cjs preserves the order of execution of code. Esm imports all modules before the file's code is run.
{% endhint %}

HT\_MODE needs to be set on boot

{% code fullWidth="false" %}

```bash
HT_MODE=RECORD node my-app.js

OR

export HT_MODE=RECORD
node my-app.js
```

{% endcode %}

#### 2.3 Set env if opentelemetry is already being used.

```
// Set this on top inside your JS app
process.env.APPLY_HT_OTEL_PATCH = 'yes'; // Set this env only if opentelemetry is already being used in your application.
```

## 3. Verifying traffic is captured

Start sending http requests on your app running with hypertest sdk.

You should start seeing requests under All requests section on the dashboard

<figure><img src="/files/krogi7xn6W8mvMdR4l2e" alt=""><figcaption></figcaption></figure>


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