Getting Started with n8n Code Node for JavaScript

Learn to use the n8n Code Node effectively for writing custom JavaScript workflows. This guide walks you through its setup, key features, limitations, and common mistakes to avoid.

Understanding the n8n Code Node

The n8n Code Node enables users to write multi-line JavaScript or Python code within an n8n workflow. It is especially useful for complex data transformations, logical operations, or tasks that exceed the limitations of n8n's expressions. The Code Node executes as a single step in your workflow, either for all inputs at once or individually for each item, depending on its mode configuration.

Prerequisites for Using the Code Node

Before you start using the Code Node, ensure you meet the following requirements:

Steps to Create a Workflow with the Code Node

This section provides step-by-step instructions to integrate the Code Node into your workflow.

Writing JavaScript in the Code Node

Below is a practical example of using the Code Node to calculate the total order values from sample order data retrieved from Google Sheets.

const inputData = $input.all();
let orderTotals = {};

// Parse input data to calculate totals
inputData.forEach(item => {
    // Access data fields using item.json
    const orderId = item.json.order_id;
    const price = parseFloat(item.json.total_price);

    if (!orderTotals[orderId]) {
        orderTotals[orderId] = 0;
    }
    orderTotals[orderId] += price;
});

// Format output into n8n-compatible JSON array structure
const outputData = Object.keys(orderTotals).map(orderId => ({
    json: {
        order_id: orderId,
        order_total: orderTotals[orderId].toFixed(2)
    }
}));

return outputData;

• $input.all() retrieves all input items into a single array.
• The orderTotals object is used to accumulate totals for each unique order.
• The result is returned as a JSON array to meet n8n's expected output format.

Limits and Alternatives for Code Node Usage

When using the Code Node, there are some important limitations to consider:

Output Data Structure in n8n

The output of every node in n8n, including the Code Node, must be an array of JSON objects. This structure allows seamless processing between nodes. Here's an example of the expected structure:

{
    "order_id": "001",
    "order_total": 500
}

[
    {
        "json": {
            "order_id": "001",
            "order_total": 500
        }
    }
]

For binary data (e.g., files or images), you must include a binary field in addition to the json structure.

Takeaways

Official reference: n8n documentation.