Best Practices

SSJS best practices for debugging, performance, security, coding style, defensive programming, and error logging.

Writing robust SSJS requires understanding both the capabilities and the sharp edges of the SFMC platform. This section consolidates practical guidance from community experts and real-world SFMC implementations.

In This Section

Page	Description
Debugging	Techniques for debugging SSJS in all execution contexts
Performance	Minimize page load times and avoid timeouts
Security	Protect against injection, CSRF, and data exposure
Style Guide	Consistent, readable SSJS code conventions
Defensive Coding	Guard against null values, empty strings, and unexpected inputs
Error Logging	Capture and persist errors for debugging and monitoring

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Top 10 SSJS Rules

1. Always Platform.Load("core", "1.1.5") first — before any Core library usage
2. Read GetPostData() once — store in a variable immediately, it returns "" on second call
3. Use + "" before ParseJSON() — ParseJSON(str + "") not ParseJSON(str) to avoid 500 errors
4. Never trust user input — validate and sanitize all query params, POST fields, and cookies
5. Use var everywhere — let, const, arrow functions, and template literals all throw runtime errors
6. Add filter to de.Rows.Retrieve() on CloudPages — it returns empty without a filter
7. Handle the switch default bug — test your switch statements, use if/else as fallback
8. Log errors to a DE — don’t rely on SFMC’s native error pages for debugging
9. Set content type explicitly — always call Platform.Response.SetContentType("application/json") for API responses
10. Use WSProxy over CreateObject/Invoke — WSProxy is simpler and more maintainable