UI Policies and Client Scripts are both client-side tools in ServiceNow that control form behavior, but they serve different purposes and have distinct characteristics.
UI Policies are declarative, no-code solutions designed for administrators to manage form field behavior. They allow you to make …UI Policies and Client Scripts are both client-side tools in ServiceNow that control form behavior, but they serve different purposes and have distinct characteristics.
UI Policies are declarative, no-code solutions designed for administrators to manage form field behavior. They allow you to make fields mandatory, read-only, or visible/hidden based on specific conditions. UI Policies are easier to create and maintain because they use a point-and-click interface rather than requiring JavaScript knowledge. They execute in a specific order based on their order field value and can be set to run on form load, on change, or both. UI Policies are ideal for simple field manipulations and are generally recommended as the first choice for basic form control needs.
Client Scripts, on the other hand, are code-based solutions that require JavaScript programming. They offer much more flexibility and power, allowing developers to perform complex operations such as field validation, asynchronous server calls using GlideAjax, alert messages, and manipulation of multiple fields simultaneously. Client Scripts come in four types: onLoad (runs when form loads), onChange (triggers when a specific field value changes), onSubmit (executes before form submission), and onCellEdit (runs when list editing occurs).
Key differences include:
1. Complexity: UI Policies handle simple scenarios; Client Scripts manage complex logic.
2. Skill requirement: UI Policies need no coding; Client Scripts require JavaScript expertise.
3. Performance: UI Policies are generally lighter weight and execute after Client Scripts.
4. Execution order: Client Scripts run before UI Policies, which can override Client Script field settings.
5. Maintenance: UI Policies are easier to troubleshoot and modify.
Best practice recommends using UI Policies whenever possible for maintainability, reserving Client Scripts for scenarios requiring advanced functionality that UI Policies cannot accomplish.
UI Policies vs Client Scripts in ServiceNow
Why This Topic Is Important
Understanding the difference between UI Policies and Client Scripts is crucial for the ServiceNow CSA exam. Both are client-side tools that modify form behavior, but knowing when to use each one demonstrates your ability to implement efficient, maintainable solutions. Exam questions frequently test your ability to choose the appropriate tool for specific scenarios.
What Are UI Policies?
UI Policies are a no-code or low-code approach to dynamically changing the behavior of form fields. They allow administrators to:
• Make fields mandatory • Make fields read-only • Show or hide fields • Set field values
UI Policies are configured through a form-based interface and require minimal scripting knowledge. They run on the client side when a form loads or when a specified field value changes.
What Are Client Scripts?
Client Scripts are JavaScript-based scripts that run in the user's browser. They provide more flexibility and control than UI Policies. The four types are:
• onLoad - Runs when a form is first displayed • onChange - Runs when a specific field value changes • onSubmit - Runs when a form is submitted • onCellEdit - Runs when a cell is edited in a list
Key Differences
Complexity: UI Policies are simpler and require less technical expertise. Client Scripts require JavaScript knowledge.
Capabilities: UI Policies handle basic field manipulations. Client Scripts can perform complex logic, make server calls using GlideAjax, and validate data on submission.
Maintenance: UI Policies are easier to maintain and troubleshoot. Client Scripts require debugging skills.
Performance: UI Policies are generally optimized by ServiceNow. Poorly written Client Scripts can impact performance.
When to Use UI Policies
• Making fields mandatory based on conditions • Hiding or showing fields dynamically • Setting fields to read-only • Setting default field values based on other field values • When you need a simple, maintainable solution
When to Use Client Scripts
• Complex validation logic before form submission • Performing calculations across multiple fields • Making asynchronous server calls • Displaying alerts or confirmation messages • Manipulating form elements beyond basic field properties
How They Work Together
UI Policies and Client Scripts can coexist on the same form. UI Policies run after Client Scripts of the same type. Both can be used together when you need simple field manipulations handled by UI Policies and complex logic handled by Client Scripts.
Exam Tips: Answering Questions on UI Policies vs Client Scripts
1. Default to UI Policies for simple tasks: If a question asks about making a field mandatory, read-only, or hidden based on a condition, UI Policies are typically the correct answer.
2. Choose Client Scripts for complex scenarios: Questions involving form submission validation, server-side data retrieval, or complex calculations point toward Client Scripts.
3. Look for keywords: Terms like no-code, administrator-friendly, or configuration suggest UI Policies. Terms like JavaScript, onSubmit, or GlideAjax indicate Client Scripts.
4. Remember the onSubmit advantage: Only Client Scripts can run logic when a form is submitted. UI Policies cannot intercept form submissions.
5. Consider maintainability: ServiceNow best practices favor UI Policies over Client Scripts when either could accomplish the task, because they are easier to maintain.
6. Reverse scenarios: If a question asks why something should NOT be used, remember that Client Scripts should not be used for simple field manipulations that UI Policies can handle.
7. Execution order matters: Remember that Client Scripts execute before UI Policies of the same type, which can be relevant in troubleshooting scenarios.