Develop a JavaScript application that fetches data from a public API, processes it, and inserts the processed data into a PostgreSQL database using prepared statements.

To create a JavaScript application that fetches data from a public API, processes it, and inserts the processed data into a PostgreSQL database using prepared statements, you can follow these steps:

1. Install Node.js: Download and install Node.js from https://nodejs.org/.

2. Create a new directory for your project and navigate to it in the terminal.

3. Initialize a new Node.js project by running `npm init -y` in the terminal. This will create a package.json file with default settings.

4. Install required dependencies:
   ```
   npm install axios pg
   ```

5. Create a `.env` file in the root of your project folder to store your PostgreSQL connection details (replace placeholders with your actual credentials):
   ```
   PGHOST=your_host
   PGUSER=your_user
   PGPASSWORD=your_password
   PGDATABASE=your_database
   PGPORT=5432
   ```

6. Create a new file named `index.js` in the root of your project folder and add the following code:

```javascript
require('dotenv').config();
const axios = require('axios');
const { Pool } = require('pg');

// Set up PostgreSQL connection
const pool = new Pool({
  host: process.env.PGHOST,
  user: process.env.PGUSER,
  password: process.env.PGPASSWORD,
  database: process.env.PGDATABASE,
  port: process.env.PGPORT,
});

// Fetch data from public API
async function fetchData() {
  try {
    const response = await axios.get('https://jsonplaceholder.typicode.com/posts');
    return response.data;
  } catch (error) {
    console.error(`Error fetching data: ${error}`);
  }
}

// Process data and insert into PostgreSQL
async function processDataAndInsert(data) {
  // Prepare SQL statement
  const sql = 'INSERT INTO posts (id, title, body) VALUES ($1, $2, $3)';

  // Connect to PostgreSQL
  const client = await pool.connect();

  try {
    for (const item of data) {
      // Process data (example: convert title to uppercase)
      const processedTitle = item.title.toUpperCase();

      // Insert into database using prepared statement
      await client.query(sql, [item.id, processedTitle, item.body]);
    }
    console.log('Data inserted successfully');
  } catch (error) {
    console.error(`Error inserting data: ${error}`);
  } finally {
    // Release the connection back to the pool
    client.release();
  }
}

// Main function
async function main() {
  const data = await fetchData();
  if (data) {
    await processDataAndInsert(data);
  }
}

main();
```

7. Before running the script, make sure you have a table named `posts` in your PostgreSQL database with columns `id`, `title`, and `body`. You can create it using the following SQL command:

```sql
CREATE TABLE posts (
  id SERIAL PRIMARY KEY,
  title VARCHAR(255),
  body TEXT
);
```

8. Run the script by executing `node index.js` in the terminal. The application will fetch data from the public API, process it, and insert the processed data into the PostgreSQL database using prepared statements.

Note that this is just a simple example, and you may need to modify the code according to your specific requirements and API endpoints.