Script Task ⚡

Executes JavaScript or Python code directly within the workflow.

Node type: scriptTask Category: Logic Actor: scriptTask (2 threads)

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Description

The Script Task runs arbitrary code for data transformation, computation, custom logic, or string manipulation. Scripts are executed in an isolated GraalVM Polyglot sandbox — they cannot access the file system, network, or JVM classes directly.

Scripts receive all current workflow variables as inputs and can set new variables or override existing ones by returning a result object.

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Properties

Property	Type	Required	Description
scriptFormat	select	Yes	javascript or python
script	code	Yes	The script body to execute

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Script Environment

Available Variables

All current workflow variables are injected into the script execution context:

// All these are automatically available:
console.log(customerName);    // workflow variable {customerName}
console.log(orderTotal);      // workflow variable {orderTotal}
console.log(items);           // workflow variable {items} (if it's an array/object)

Returning Results

Return an object to set or update workflow variables:

return {
  formattedTotal: `$${parseFloat(orderTotal).toFixed(2)}`,
  itemCount: items.length,
  isLargeOrder: parseFloat(orderTotal) > 1000
};

After this script runs, {formattedTotal}, {itemCount}, and {isLargeOrder} are available to all downstream nodes.

If the script returns null or nothing, no variables are modified.

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JavaScript Examples

String Manipulation

// Normalize phone number to E.164 format
const digits = phoneNumber.replace(/\D/g, '');
const e164 = digits.startsWith('1') ? `+${digits}` : `+1${digits}`;

return {
  normalizedPhone: e164,
  phoneValid: e164.length === 12
};

Date Formatting

// Format a date for email display
const date = new Date(appointmentTimestamp);
const formatted = date.toLocaleDateString('en-US', {
  weekday: 'long',
  year: 'numeric',
  month: 'long',
  day: 'numeric',
  hour: '2-digit',
  minute: '2-digit'
});

return { formattedDate: formatted };

Data Transformation

// Transform API response array into summary stats
const orders = JSON.parse(ordersJson);

const total = orders.reduce((sum, o) => sum + o.amount, 0);
const avgOrder = total / orders.length;
const highestOrder = Math.max(...orders.map(o => o.amount));

return {
  orderCount: orders.length,
  totalRevenue: total.toFixed(2),
  averageOrder: avgOrder.toFixed(2),
  highestOrder: highestOrder.toFixed(2)
};

Conditional Processing

// Parse AI classification response and validate
let classification;
try {
  const parsed = JSON.parse(aiResponse);
  classification = parsed.classification;
} catch (e) {
  // Fallback if AI returned non-JSON
  classification = 'general';
}

const validClasses = ['billing', 'technical', 'account', 'general'];
const isValid = validClasses.includes(classification);

return {
  classification: isValid ? classification : 'general',
  classificationConfident: isValid
};

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Python Examples

# Calculate order discount
discount_rate = 0.15 if float(orderTotal) > 500 else 0.05
discount_amount = float(orderTotal) * discount_rate
final_total = float(orderTotal) - discount_amount

return {
    "discountRate": discount_rate,
    "discountAmount": round(discount_amount, 2),
    "finalTotal": round(final_total, 2)
}

# Parse and validate email list
emails = recipientEmails.split(',')
valid_emails = [e.strip() for e in emails if '@' in e and '.' in e.split('@')[-1]]

return {
    "validEmails": valid_emails,
    "emailCount": len(valid_emails),
    "hasValidEmails": len(valid_emails) > 0
}

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Sandbox Restrictions

Scripts run in GraalVM Polyglot sandbox with these restrictions:

Capability	Available?
Standard math/string/array operations	✅
JSON.parse / JSON.stringify	✅
Date operations	✅
Regular expressions	✅
console.log (captured in execution logs)	✅
File system access	❌
Network calls (fetch, http)	❌
JVM class access	❌
require() / import (external modules)	❌

For network calls or external integrations, use the appropriate Service Task nodes instead.

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Error Handling

Scenario	Behavior
Script throws an uncaught exception	Node fails, error message in {_error}, takes errorFlow
Script returns non-object	No variables modified, execution continues
Script syntax error	Node fails immediately at execution start
Timeout exceeded	Takes timeoutFlow; script is interrupted

// Good pattern: wrap risky operations in try/catch
try {
  const data = JSON.parse(rawApiResponse);
  return { parsedData: data, parseSuccess: true };
} catch (e) {
  return { parsedData: null, parseSuccess: false, parseError: e.message };
}

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Connections

Condition	Connection
Script completed without error	successFlow or sequenceFlow
Script threw uncaught exception	errorFlow
Timeout	timeoutFlow

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Best Practices

• Wrap risky operations (JSON.parse, type conversions) in try/catch
• Always return an object — this makes variable changes explicit
• Set a timeout (5–10 seconds) — infinite loops will block the actor thread
• Log intermediate values with console.log() — they appear in execution logs
• Keep scripts focused on one transformation — chain multiple Script Tasks for complex processing
• Test scripts locally before deploying (they're pure functions with simple inputs)