Convert Between Data Formats Using Code Nodes

When APIs speak different languages -- one returns JSON, another expects CSV, a third emits XML -- the Code node is your universal translator. The Code node sandbox includes JSON natively and you can parse or build any text format with standard JavaScript string operations.

Real-world example: A REST API returns a JSON array of invoices. You need to convert it to a CSV file and attach it to an outgoing email via the Send Email node.

// Code node — Run Once for All Items
const items = $input.all();

// Build CSV header
const headers = ['invoice_id', 'customer', 'amount', 'currency', 'date'];
let csv = headers.join(',') + '\n';

// Build CSV rows
for (const item of items) {
  const row = [
    item.json.invoice_id,
    `"${item.json.customer_name.replace(/"/g, '""')}"`, // escape quotes
    item.json.total_amount,
    item.json.currency,
    item.json.invoice_date
  ];
  csv += row.join(',') + '\n';
}

// Return as binary data for email attachment
const binaryData = await this.helpers.prepareBinaryData(
  Buffer.from(csv, 'utf-8'),
  'invoices.csv',
  'text/csv'
);

return [
  {
    json: { rowCount: items.length },
    binary: { data: binaryData }
  }
];
```text
In the Send Email node, set the attachment to the `data` binary property. The recipient gets a clean CSV file attached to the email.

> **Tip: XML Parsing**
>
> For XML-to-JSON conversion, use the built-in XML node or the `xml2js` library available in the Code node: `const { parseStringPromise } = require('xml2js');`

This pattern is critical for integrations between modern APIs and legacy systems that only accept flat file formats.

**Related:** [Flatten Deeply Nested API Responses](../code-node-mastery/01-flatten-deeply-nested-api-responses.md) | [Use the HTTP Request Node as a Universal Connector](../integration-patterns/01-use-the-http-request-node-as-a-universal-connector.md)