Function Node

The Function node runs your own JavaScript code in a secure sandbox. Use it when transforms aren't enough and you need full programmatic control.

Writing function code

Open the Function node and write code in the built-in editor. Click Variables to insert data references at your cursor.

Default template

// Access workflow data
const inputs = {{inputs}};
const lastOutput = {{lastOutput}};
const variables = {{variables}};
const context = {{context}};

// Your custom logic here
const result = {
  processed: true,
  data: lastOutput,
};

// Return the result
return result;

Rules

1. JavaScript only — Python and other languages are not supported in Function nodes.
2. Must return a value — the returned object becomes the node's output for downstream steps.
3. Read-only scope — inputs, lastOutput, and variables are read-only; mutating them won't affect other nodes.
4. Size limit — code must be under 10 KB.
5. No network or filesystem — fetch, require, process, and file system access are blocked for security.

Examples

Calculate a total

const items = lastOutput.items || [];
const total = items.reduce((sum, item) => sum + (item.price || 0), 0);

return {
  items,
  total,
  currency: variables.currency || 'USD',
};

Format data for an API

return {
  recipient: inputs.email,
  subject: `Order #${lastOutput.orderId} confirmed`,
  body: `Hi ${lastOutput.customerName},\n\nYour order of $${lastOutput.amount} has been confirmed.`,
};

Parse and validate

const raw = lastOutput.content || '';
let parsed;

try {
  parsed = JSON.parse(raw);
} catch {
  return { error: 'Invalid JSON from AI node', raw };
}

if (!parsed.email) {
  return { error: 'Missing email field', parsed };
}

return { valid: true, ...parsed };

Filter and transform a list

const records = lastOutput.data || [];

return {
  active: records.filter(r => r.status === 'active'),
  inactive: records.filter(r => r.status !== 'active'),
  count: records.length,
};

Available scope

Inside a Loop node, you also have access to loopItem and loopIndex.

Editor features

• Syntax highlighting and line numbers
• Expand to full-screen editor for longer scripts
• Variable inserter — click Variables to browse and insert {{paths}}
• Template placeholders like {{inputs}} are replaced with actual values before your code runs

Error handling

If your code throws an error or has a syntax issue, the node fails and the error appears in the Execution Data tab. Common mistakes:

Function vs Transform Code

Both support JavaScript, but they serve different purposes:

Tips

• Start with the default template and modify incrementally.
• Test with a Manual trigger and check Execution Data after each change.
• Keep functions small and focused — chain multiple Function nodes for complex pipelines.
• Use Transform → Edit Fields for simple renaming; reserve Function for real logic.