🎯 Deep Dive into Client-side & Server-side Scripting – Tools, Classes & Use Cases

[Bhavesh Patil]

Hey #ServiceNowCommunity 👋

Whether you're just starting out or refining your development skills, understanding where and how your scripts run is fundamental to building smart, efficient apps on the ServiceNow platform.

From making forms dynamic in real time to running powerful back-end logic — scripting powers almost everything in ServiceNow.
This guide will help you confidently navigate both client-side and server-side scripting, their core classes, and when to use what.

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🔄 What You'll Learn

• Client-side vs Server-side scripting

• Common scripting classes and APIs

• Real-world examples and best practices

• Key ServiceNow scripting tools

• Common pitfalls and pro tips

Let’s dive in 👇

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⚔️ Client-side vs Server-side Scripting in ServiceNow

Aspect	Client Side Scripting	Server Side Scripting
Runs On	User's web browser	ServiceNow server
Trigger Events	Form load, field value change, button click	Record insert/update/delete, Business Rules, Scheduled Jobs
Primary Purpose	Manage UI behavior, validate input before submission	Business logic, database operations, integrations
Use Cases	Dynamic forms, field validation, real-time feedback	Record creation, data updates, notifications, API calls
Execution Speed	Instant (local to browser)	Slower due to server round-trips but more powerful

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📚 Commonly Used Classes

🖥️ Client-side Classes

Class Class	Description
GlideForm	Control form fields (hide/show, mandatory, readonly, etc.)
GlideUser	Get info about the logged-in user
GlideAjax	Call server-side logic from client-side
GlideDialogWindow	Display modal dialog windows
GlideMenu	Customize right-click/context menus

 

⚙️ Server-side Classes

Class	Description
GlideRecord	Interact with database records (CRUD operations)
GlideAggregate	Perform aggregate queries like COUNT, AVG, etc.
GlideSystem (gs)	Utility methods: logging, messaging, user info
GlideDateTime	Handle and format dates and times
GlideSecure	Manage encryption, hashing, and security operations

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🧠 Quick Summary

✅ Use Client-side scripting to enhance user experience — dynamic form behavior, instant validation, or conditional UI logic.
✅ Use Server-side scripting to handle data operations — querying records, processing logic, sending notifications, or calling APIs.
✅ Choose the right class and scope based on what your script needs to accomplish.

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⚠️ Common Mistakes to Avoid

• Using update() inside loops without batching

• Overloading client-side scripts with heavy logic

• Duplicating logic across multiple Business Rules

• Making Script Includes publicly accessible without need

• Ignoring ACLs and user role conditions during testing

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💡 Pro Tips

• Use GlideDateTime for accurate, timezone-safe date/time operations

• Leverage gs.getUser() and gs.getSession() for session-aware logic

• Debug GlideAjax using the browser’s DevTools → Network tab

• Use gs.eventQueue() to trigger custom events and notifications

• Combine Script Includes with Flow Designer for clean, reusable automation

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🧭 Final Thoughts

Scripting is what makes ServiceNow so powerful and flexible. By mastering client-side and server-side scripting, and applying the right classes at the right time, you can build smarter, faster, and more maintainable applications.

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