JS Code

Executes custom JavaScript code to transform items.

Overview

The JS Code node runs JavaScript for each item, giving you full programming control over transformations. Use it for:

• Complex calculations
• Custom data parsing
• Conditional logic
• String manipulation
• Data validation

Parameters

Parameter	Description	Required
JS Code	JavaScript code to execute	Yes

Code

Write JavaScript that processes the item. The code has access to:

• item - The current input item

Return the transformed item, a new object, or an array of items.

Output

The return value of your code becomes the output. If you return an array, each element becomes a separate output item.

Input:

{ "firstName": "John", "lastName": "Doe", "price": "19.99" }

Code:

return {
  fullName: item.firstName + ' ' + item.lastName,
  price: parseFloat(item.price),
  formattedPrice: '$' + parseFloat(item.price).toFixed(2)
};

Output:

{
  "fullName": "John Doe",
  "price": 19.99,
  "formattedPrice": "$19.99"
}

Examples

Parse JSON String

const data = JSON.parse(item.jsonString);
return {
  ...item,
  parsedData: data
};

Conditional Transformation

const status = item.amount > 1000 ? 'high' : 'normal';
const priority = item.urgent ? 1 : 2;

return {
  ...item,
  status,
  priority
};

String Manipulation

return {
  ...item,
  email: item.email.toLowerCase().trim(),
  slug: item.title.toLowerCase().replace(/\s+/g, '-'),
  initials: item.firstName[0] + item.lastName[0]
};

Date Handling

const date = new Date(item.timestamp);
return {
  ...item,
  year: date.getFullYear(),
  month: date.getMonth() + 1,
  day: date.getDate(),
  formatted: date.toISOString().split('T')[0]
};

Array Processing

const tags = item.tagString.split(',').map(t => t.trim());
const uniqueTags = [...new Set(tags)];

return {
  ...item,
  tags: uniqueTags,
  tagCount: uniqueTags.length
};

Validation

const errors = [];

if (!item.email || !item.email.includes('@')) {
  errors.push('Invalid email');
}

if (!item.name || item.name.length < 2) {
  errors.push('Name too short');
}

return {
  ...item,
  isValid: errors.length === 0,
  validationErrors: errors
};

Return Multiple Items

// Split one item into multiple
return [
  { type: 'header', data: item.header },
  { type: 'body', data: item.body },
  { type: 'footer', data: item.footer }
];

Object Restructuring

return {
  customer: {
    name: item.customerName,
    email: item.customerEmail
  },
  order: {
    id: item.orderId,
    total: item.orderTotal
  }
};

Available Context

Variable	Description
item	Current input item object

Tips

• Always return an object or array (the output item(s))
• Use ...item spread to preserve existing fields
• Code runs in an isolated JavaScript VM
• Errors in code create error items
• Return an array to output multiple items from one input
• Test with sample data before running on full dataset
• Complex logic is fine, but keep it readable