Client Scripts in ServiceNow are JavaScript code that runs on the client-side (in the user's web browser) to enhance form functionality and user experience. There are four main types of Client Scripts that every ServiceNow Administrator should understand.
**1. onLoad Client Scripts**
These scripts…Client Scripts in ServiceNow are JavaScript code that runs on the client-side (in the user's web browser) to enhance form functionality and user experience. There are four main types of Client Scripts that every ServiceNow Administrator should understand.
**1. onLoad Client Scripts**
These scripts execute when a form is first loaded in the browser. They are commonly used to set default field values, hide or show form sections, make fields mandatory, or display informational messages to users when they open a record.
**2. onChange Client Scripts**
These scripts trigger when a specific field value changes on the form. They are useful for creating dynamic form behavior, such as populating related fields based on a selection, validating field entries in real-time, or showing alerts when certain values are selected.
**3. onSubmit Client Scripts**
These scripts run when a user attempts to save or submit a form. They are primarily used for form validation before the data is sent to the server. If validation fails, the script can prevent the form submission and display an error message to the user.
**4. onCellEdit Client Scripts**
These scripts execute when a user edits a cell in a list view using list editing functionality. They allow validation and dynamic behavior when users make changes through the list interface rather than opening the full form.
**Key Considerations:**
- Client Scripts only run in the browser and do not execute during server-side operations like imports or web service calls
- They should be kept lightweight to maintain good form performance
- Use the g_form API to interact with form elements and the g_user API to access current user information
- Always specify the table and conditions carefully to ensure scripts run only when needed
Understanding these Client Script types enables administrators to create responsive, user-friendly forms that guide users through data entry effectively.
Client Script Types in ServiceNow
Why Client Script Types Are Important
Client scripts are fundamental to creating dynamic, responsive user interfaces in ServiceNow. Understanding the different types of client scripts is essential for the CSA exam because they control how forms behave when users interact with them. Mastering this topic enables you to improve user experience, enforce business rules on the client side, and reduce unnecessary server calls.
What Are Client Script Types?
Client scripts are JavaScript code that runs in the user's web browser when they interact with forms in ServiceNow. There are four main types of client scripts:
1. onLoad Executes when a form is first loaded or displayed to the user. Use this to set default values, hide or show fields, or make fields mandatory when the form opens.
2. onChange Runs when a specific field value changes on the form. This script type requires you to specify which field triggers the script. Use this for dynamic field behavior based on user input.
3. onSubmit Executes when a user saves or submits the form. This is ideal for validation before data is sent to the server. If the script returns false, the submission is cancelled.
4. onCellEdit Runs when a user edits a field in a list view using list editing. This allows validation and manipulation of data edited in list format.
How Client Scripts Work
Client scripts operate in the browser and use the GlideForm (g_form) API to interact with form elements. Key functions include:
- g_form.getValue('field_name') - Gets a field's value - g_form.setValue('field_name', 'value') - Sets a field's value - g_form.setMandatory('field_name', true/false) - Makes a field required - g_form.setVisible('field_name', true/false) - Shows or hides a field - g_form.setReadOnly('field_name', true/false) - Makes a field read-only
Client scripts are table-specific and can be set to run on insert, update, or both operations.
Exam Tips: Answering Questions on Client Script Types
1. Know the triggers: Remember that onLoad fires when the form opens, onChange fires when a field changes, onSubmit fires on save, and onCellEdit fires during list editing.
2. onChange requires a field: When configuring an onChange script, you must specify which field triggers it. This is a common exam question.
3. onSubmit returns false to cancel: If an onSubmit script returns false, the record will not be saved. This is used for validation purposes.
4. Client vs Server: Client scripts run in the browser and cannot access server-side APIs like GlideRecord. Know the distinction between client-side and server-side scripting.
5. Performance consideration: Client scripts affect form load time. The exam may ask about best practices for performance.
6. UI Policies vs Client Scripts: Understand that UI Policies are often preferred for simple field manipulations because they require no coding and are easier to maintain.
7. Common scenario questions: Expect questions like 'Which client script type would you use to validate data before saving?' (Answer: onSubmit) or 'Which type runs when the form first displays?' (Answer: onLoad).
8. Remember the g_form API: Many questions involve knowing which g_form methods to use for specific tasks like hiding fields or making them mandatory.