🚀 n8n Code Node: Essential Syntax & Debugging Tips You Must Know!

D: n8n’s Code Node is a powerful tool that lets you write custom JavaScript/Python snippets to manipulate data, call APIs, or automate complex logic. But mastering it requires understanding key syntax and debugging techniques. Let’s break it down!

🔧 1. Essential Code Node Syntax

A. Accessing Input Data

Use $input to access data from previous nodes. For example:

// Get data from the first input item
const data = $input.all()[0].json;
return { payload: data.name.toUpperCase() };

• $input.all(): Returns an array of all input items.
• .json: Accesses the JSON payload.

B. Returning Output

Always return an object with an array. Example:

return {
  json: { 
    userId: 123,
    status: "processed" 
  }
};

C. Using Libraries (JavaScript)

n8n supports built-in libraries like lodash or moment:

const _ = require('lodash');
return { json: _.capitalize("hello world") }; // Output: "Hello world"

D. Python Example

For Python, use the pd (Pandas) or requests library:

import requests
response = requests.get("https://api.example.com")
return [{ "data": response.json() }]

🐞 2. Debugging Like a Pro

A. console.log is Your Friend

Use console.log() to inspect variables:

const rawData = $input.all();
console.log("DEBUG:", rawData); // Check in the "Execution" tab!

B. Handle Errors Gracefully

Wrap code in try-catch:

try {
  const riskyData = $input.first().json.nonexistent.field;
} catch (error) {
  console.log("Error caught:", error.message);
  return { json: { error: "Safe fallback" } };
}

C. Validate Data Structure

Check if fields exist before accessing:

const user = $input.first().json;
if (user?.address?.city) {  // Optional chaining
  return { json: { city: user.address.city } };
}

D. Use the “Test Step” Button

👉 Click “Execute Node” to preview outputs without running the full workflow!

💡 3. Pro Tips

1. Reuse Code: Save snippets in the “Code Snippets” section (Settings → Community Nodes).
2. Environment Variables: Store API keys securely via $env.VAR_NAME.
3. Async/Await: For API calls, use promises:

   const result = await fetch("https://api.example.com");
   return { json: await result.json() };

🎯 Real-World Example

Scenario: Extract emails from a CSV, validate domains, and return clean data.

const items = $input.all();
const validEmails = items.map(item => {
  const email = item.json.email;
  if (email.includes("@company.com")) {
    return { json: { validEmail: email } };
  }
});
return validEmails.filter(Boolean);

🔥 Final Advice

• Start small: Test one function at a time.
• Document: Add comments for complex logic.
• Community Help: Join the n8n Slack for support!

Now go build something amazing! 🚀

(Need more? Check n8n’s official docs!)