Function Block

The Function block lets you run custom JavaScript code inside your workflow. Use it for data transformation, formatting, calculations, API response parsing, or any logic that doesn't need a dedicated block.

Overview

When to Use

• Transform or reshape data between blocks
• Parse JSON, extract fields, or format strings
• Perform calculations or date math
• Filter arrays or aggregate data
• Build custom logic not covered by other blocks

Configuration

Code Editor

Write JavaScript that processes inputs and returns results. Access block outputs via the inputs parameter.

// Access previous block outputs
const data = inputs.agent.content;
const parsed = JSON.parse(data);

// Transform and return
return {
  names: parsed.users.map(u => u.name),
  count: parsed.users.length,
  timestamp: new Date().toISOString()
};

Inputs Table

Define named inputs that map to other block outputs. Each input has:

• Name — Variable name accessible in your code
• Value — Block reference (e.g., {{agent.content}})

Outputs

Example: Format API Response

Goal: Extract and reshape JSON from an API call.

Workflow:

[Starter] → [API Block] → [Function] → [Slack]

Inputs:

Code:

const data = JSON.parse(inputs.apiResult);

// Extract just what Slack needs
const summary = data.results.map(item => {
  return `• ${item.title} — $${item.price}`;
}).join('\n');

return {
  message: `Found ${data.results.length} items:\n${summary}`,
  total: data.results.reduce((sum, item) => sum + item.price, 0)
};

Slack message uses: {{function.result.message}}

Tips

• Always JSON.parse() when receiving string-encoded JSON from Agent or API blocks
• Return an object with named fields for easy downstream access ({{function.result.fieldName}})
• Use for data cleanup — trim strings, fix casing, merge arrays, etc.
• Debug with console.log() — output appears in execution logs