Mastering ServiceNow Scripting: A Comprehensive Guide (Basic of JavaScripting and Live Coding)

[BillMartin]

As a Certified ServiceNow Instructor, I have created this article to assist aspirants, developers, and implementers alike.

This guide aims to give you a comprehensive picture of the fundamentals of ServiceNow scripting. Whether you're a novice trying to get started or an experienced developer refining your skills, these insights will help you harness the power of ServiceNow scripting effectively.

In this guide, I will walk you through the Fundamentals of ServiceNow Scripting. We will begin with an overview, followed by the big WHY/WHEN to script in ServiceNow , and cover the three key concepts. Afterward, we’ll do a deep dive with examples, touch on best practices, explore common use cases, and finish with a conclusion. Finally, I’ll close out with a live demo to give you hands-on experience.

Overview: Why Scripting in ServiceNow Matters

ServiceNow offers powerful out-of-the-box capabilities, but scripting is the key to extending its potential. Through scripting, you can build solutions tailored to specific business needs, automate complex tasks, and create dynamic workflows that seamlessly adapt to changing requirements.

The Big WHY and WHEN to Script in ServiceNow

There are two key questions we must answer before diving into the fundamentals of scripting: Why should you script in ServiceNow? and When is scripting necessary?

Why Script in ServiceNow?

• Customization: Tailor existing modules and applications to meet unique business requirements.
• Automation: Reduce manual intervention by automating repetitive tasks, workflows, and processes.
• Efficiency: Enhance system performance, improve response times, and optimize operations through custom scripts.
• Integration: Enable seamless communication with external systems via APIs and web services.

When Should You Script?

Scripting should be used when:

• Out-of-the-box solutions are insufficient for business needs.
• Complex logic needs to be applied to processes or workflows.
• Automation is required beyond basic configuration, such as complex decision-making based on user input.
• Integration with external systems or custom web services is necessary.

However, scripting should be avoided when simple configurations or low-code solutions like Flow Designer or UI Policies suffice. Always weigh the necessity of scripting against maintainability and performance.

Three Key Concepts in ServiceNow Scripting

Understanding these three concepts will be fundamental as you begin scripting in ServiceNow:

1. Server-Side Scripting vs. Client-Side Scripting

   • Server-Side Scripting: This type of scripting executes on the server and involves business logic and database interactions (e.g., Business Rules, Script Includes, Scheduled Jobs).
   • Client-Side Scripting: This type of scripting executes in the user’s browser and controls form behaviors, user inputs, and validations (e.g., Client Scripts, UI Policies).

2. JavaScript as the Core Language

   • ServiceNow scripts are written using JavaScript, which is widely used for web development. However, ServiceNow extends JavaScript's capabilities by providing its own libraries and APIs, tailored specifically for the platform.

3. Glide API

   • The Glide API is a collection of ServiceNow-specific classes and methods designed to interact with the platform's services. The API includes classes like GlideRecord for database manipulation, GlideSystem for system utilities, and GlideAjax for asynchronous communication between client and server.

Deep Dive: ServiceNow Scripting Examples

Let’s delve deeper into scripting, starting with examples of both client-side and server-side scripting.

Client-Side Scripting

Client-side scripting is all about improving the user experience by modifying form behaviors, validating inputs, and dynamically updating fields. A common example of client-side scripting is a Client Script that auto-populates fields based on user input.

Example: Auto-Fill Priority Based on Impact

function onChange(control, oldValue, newValue, isLoading) {
if (isLoading || newValue === '') {
return;
}
if (newValue == 'high') {
g_form.setValue('priority', '1');
}
}

This script automatically sets the "Priority" field to 1 - Critical when the "Impact" field is set to high.

ServiceNow Server-Side Scripting

Server-side scripting involves executing logic on the server, often in response to database operations. One example is a Business Rule that prevents records from being saved if certain conditions aren't met.

Example: Business Rule to Enforce Resolution Code

(function executeRule(current, previous /*null when async*/) {
if (current.state == 'Resolved' && !current.resolution_code) {
gs.addErrorMessage('Resolution code is required before resolving an incident.');
current.setAbortAction(true);
}
})(current, previous);

This Business Rule ensures that a resolution code is entered before an incident can be marked as resolved.

ServiceNow Scripting Best Practices

As a Certified ServiceNow Instructor, I emphasize these best practices to ensure your scripts are maintainable, efficient, and secure:

1. KISS Principle (Keep It Simple, Stupid): Simplicity is key. Avoid over-complicating scripts with unnecessary logic. A clean, concise script is easier to maintain and debug.
2. Optimize GlideRecord Queries: Minimize database calls by using filters, limits, and aggregation. Always strive for efficiency.
3. Modular Code with Script Includes: Avoid code duplication by centralizing reusable functions in Script Includes.
4. Security Considerations: Validate all inputs, sanitize user-generated data, and be mindful of data exposure, especially in client-side scripts.
5. Performance Optimization: Use asynchronous processing whenever possible to avoid locking resources during long-running processes.
6. Thorough Testing: Test scripts in a sandbox environment before moving to production. This will help you catch errors early and ensure stability.

Common Use Cases for ServiceNow Scripting

To give you more context, here are some common scenarios where scripting in ServiceNow adds value:

• Automated Assignment of Incidents: Scripts automatically route incidents to the appropriate team based on criteria like priority or category.
• Custom Approval Flows: Advanced logic in workflows routes approval requests based on dynamic conditions.
• Data Validation and Enforcement: Scripting enforces business rules and ensures only valid data is stored in the system.
• API Integrations: ServiceNow scripts interact with external systems through REST or SOAP APIs, pulling and pushing data as required.

Conclusion

ServiceNow scripting allows developers and implementers to build dynamic, customized, and highly efficient solutions that meet specific business needs. By understanding the difference between client-side and server-side scripting, mastering the Glide API, and following best practices, you can create scripts that are robust, secure, and scalable.

Live Demo

As we conclude this deep dive into ServiceNow scripting fundamentals, I'll now provide a live demo to put these concepts into action.

Let’s jump into the platform and start scripting!

This guide provides a solid foundation, but remember, the real learning happens when you practice and experiment with these scripting concepts in your own ServiceNow instance. Happy scripting!

Please mark as helpful If you find this article lucrative.

[BillMartin · Accepted solution]

Hi @Nikhil Bajaj9 ,

"Thank you for taking the time to appreciate my content! Your support means a lot, and it motivates me to continue creating valuable resources. Looking forward to sharing more insights with you and the community!"

[Nikhil Bajaj9]

Thanks for sharing

[BillMartin · Accepted solution]

Hi @Nikhil Bajaj9 ,

"Thank you for taking the time to appreciate my content! Your support means a lot, and it motivates me to continue creating valuable resources. Looking forward to sharing more insights with you and the community!"

[Dr Atul G- LNG]

One more feedback from my student .

@BillMartin 

[BillMartin]

such humbling feedback @Dr Atul G- LNG , which serves as a powerful reminder of the impact and a motivator to continuously share. It's truly gratifying and deeply appreciated!