Resonance includes a powerful scripting engine that allows you to automate workflows with JavaScript. You can write pre-request scripts to modify requests before they're sent, and test scripts to validate responses and extract data.

Overview

Scripts in Resonance run in a secure sandboxed environment with a 10-second timeout. They have access to a rich API for manipulating requests, validating responses, and managing environment variables.

Accessing Scripts

1. Open the Scripts tab in the request configuration panel
2. Choose between Pre-request and Test sub-tabs
3. Write your JavaScript code in the editor
4. Scripts are auto-saved after 1 second of inactivity
5. View script output in the Scripts tab of the response panel

Pre-request Scripts

Pre-request scripts execute before sending the request. Use them to:

• Modify request headers dynamically
• Calculate authentication signatures or timestamps
• Set or update environment variables
• Modify query parameters or path parameters
• Transform request body content

Pre-request Script Example: Add Timestamp

// Add current timestamp to headers
request.headers['X-Request-Time'] = new Date().toISOString();

// Set timestamp in environment for use in other scripts
environment.set('requestTimestamp', Date.now());

console.log('Request timestamp:', request.headers['X-Request-Time']);

Pre-request Script Example: Dynamic Authentication

// Calculate HMAC signature for authentication
const secret = environment.get('apiSecret');
const timestamp = Date.now().toString();
const payload = request.method + request.url + timestamp;

// Note: This is a simplified example
// In production, you would use proper cryptographic libraries
const signature = btoa(secret + payload);

request.headers['X-Signature'] = signature;
request.headers['X-Timestamp'] = timestamp;

console.log('Authentication headers added');

Test Scripts

Test scripts execute after receiving the response. Use them to:

• Validate response status codes and headers
• Assert response body structure and content
• Extract data from responses and save to environment variables
• Chain requests by passing data between endpoints
• Measure and validate performance metrics

Test Script Example: Response Validation

// Validate status code
expect(response.status).toBe(200);

// Parse and validate response body
const data = JSON.parse(response.body);
expect(data).toBeDefined();
expect(data.id).toBeDefined();
expect(data.name).toBeTruthy();

// Check response headers
expect(response.headers['content-type']).toContain('application/json');

console.log('All validations passed');

Test Script Example: Data Extraction

// Extract authentication token from login response
const data = JSON.parse(response.body);

if (data.token) {
    // Save token to environment for use in subsequent requests
    environment.set('authToken', data.token);
    console.log('Token saved to environment');
} else {
    console.error('No token found in response');
}

// Extract user ID for next request
if (data.userId) {
    environment.set('currentUserId', data.userId);
    console.log('User ID:', data.userId);
}

Test Script Example: Performance Testing

// Validate response time
expect(response.status).toBe(200);

// Check if response was fast enough
const maxResponseTime = 1000; // 1 second
if (response.timings && response.timings.total) {
    expect(response.timings.total).toBeLessThan(maxResponseTime);
    console.log('Response time:', response.timings.total, 'ms');
}

// Validate response size
const bodySize = response.body.length;
console.log('Response size:', bodySize, 'bytes');

Script APIs

Pre-request Script APIs

Test Script APIs

Common Use Cases

Request Chaining

Use scripts to chain requests together by extracting data from one response and using it in the next request:

// In the login request test script:
const loginData = JSON.parse(response.body);
environment.set('authToken', loginData.token);

// In subsequent requests' pre-request script:
const token = environment.get('authToken');
request.headers['Authorization'] = `Bearer ${token}`;

Dynamic Data Generation

// Generate random data for testing
const randomEmail = `test${Date.now()}@example.com`;
const randomId = Math.floor(Math.random() * 10000);

// Update request body
const body = JSON.parse(request.body);
body.email = randomEmail;
body.id = randomId;
request.body = JSON.stringify(body);

console.log('Generated test data:', { email: randomEmail, id: randomId });

Conditional Logic

// Use different endpoints based on environment
const env = environment.get('environmentName');

if (env === 'production') {
    request.url = request.url.replace('staging', 'api');
    console.log('Using production endpoint');
} else {
    console.log('Using staging endpoint');
}

// Add debug header in non-production environments
if (env !== 'production') {
    request.headers['X-Debug'] = 'true';
}

Best Practices

• Keep scripts simple: Complex logic should be moved to your backend or external tools
• Use console.log liberally: Debug output helps understand script execution
• Handle errors gracefully: Use try-catch blocks for operations that might fail
• Store secrets in environment variables: Never hardcode API keys or passwords in scripts
• Use descriptive variable names: Make scripts readable and maintainable
• Comment your code: Explain what complex scripts are doing
• Test incrementally: Build scripts step by step and test as you go

Security and Limitations

• Sandboxed execution: Scripts run in a secure sandbox with no access to the file system, network, or system resources
• 10-second timeout: Scripts that run longer than 10 seconds will be terminated
• No external modules: You cannot require() or import external libraries
• Limited APIs: Only the documented APIs are available (Date, Math, JSON, console, etc.)
• No async operations: Scripts execute synchronously; promises and async/await are not supported

Troubleshooting

Script not executing

• Check the Scripts tab in the response panel for error messages
• Ensure your script doesn't have syntax errors
• Verify the script is saved (auto-save happens after 1 second)

Variables not available

• Ensure you have an active environment selected
• Check that variable names are spelled correctly
• Use console.log to verify environment.get() returns expected values

Assertions failing

• Log the actual values using console.log before asserting
• Check response.body is being parsed correctly
• Verify the API is returning the expected data structure

Next Steps

• Return to Getting Started for basic usage
• Check out Features for all capabilities
• Visit the GitHub repository for updates