Begin by ensuring you have Node.js and npm (Node Package Manager) installed on your computer. This setup is essential for running JavaScript code that interacts with Firestore. You can download and install Node.js from the official website. Verify the installation by running `node -v` and `npm -v` in your terminal.

Log into the Firebase Console (https://console.firebase.google.com/) and create a new project. Once your project is created, navigate to the Firestore section and enable Firestore by creating a new database. Choose "Start in test mode" for simplicity during development, but remember to set appropriate security rules before deploying your application.

Open a terminal and create a new directory for your project. Navigate into this directory and initialize a Node.js project using `npm init -y`. Then, install the Firebase Admin SDK by running `npm install firebase-admin`. This SDK will allow you to interact with Firestore programmatically.

In the Firebase Console, navigate to Project Settings > Service accounts. Click "Generate new private key" to download a JSON file containing your service account key. This file is required to authenticate your server-side application with Firebase. Save it securely in your project directory.

Create a new JavaScript file (e.g., `uploadData.js`) in your project directory. In this file, write a script to read from your JSON file and upload data to Firestore. Use the `fs` module to read your JSON file and the Firebase Admin SDK to authenticate and upload data to Firestore. Here is a basic template:

```javascript
const admin = require('firebase-admin');
const fs = require('fs');

// Initialize Firebase Admin SDK
const serviceAccount = require('./path/to/your/serviceAccountKey.json');
admin.initializeApp({
credential: admin.credential.cert(serviceAccount)
});

const db = admin.firestore();

// Read JSON file
const data = JSON.parse(fs.readFileSync('./path/to/your/data.json', 'utf8'));

// Upload data to Firestore
const uploadData = async () => {
const collectionRef = db.collection('your-collection-name');
for (const [key, value] of Object.entries(data)) {
await collectionRef.doc(key).set(value);
}
console.log('Data uploaded successfully!');
};

uploadData().catch(console.error);
```

Run your script from the terminal using `node uploadData.js`. This command will execute the Node.js script, read your JSON data, and upload it to the specified Firestore collection. Ensure your JSON data matches the expected structure in Firestore for smooth data upload.

After executing the script, return to the Firebase Console and navigate to the Firestore section. Check the specified collection to ensure the data from your JSON file has been correctly uploaded. If there are issues, review your script for errors and ensure your JSON structure aligns with your Firestore schema.

By following these steps, you can effectively move data from a JSON file to Google Firestore using only native tools and libraries, without relying on third-party connectors or integrations.