OnChange Client Script An onChange Client Script runs on the client side (browser) when the value of a field changes on a form.  It is mainly used to:  Show or hide fields  Make fields mandatory or read-only  Auto-populate fields  Call Script Includes using GlideAjax  Validate user input instantly  Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo. 1.1 Running onChange Client Script As onLoad Client Script When a form loads:  ServiceNow sets default values for fields  Values are populated from the database  The platform internally fires change events for those fields  Because of this, the onChange script gets executed once during form load.  1.1.1 Scenario When User is not selected, all the fields should be Read Only, and when user is selected, all the fields can be editable. Create New Client Script   Give name-> Add User Restriction, Type -> onChange, Field Name -> STS User   Add Script, comment out first “if statement” or remove it, it will make the onChnage client script run as onLoad Client Script.   Script:   function onChange(control, oldValue, newValue, isLoading, isTemplate) {  //    if (isLoading || newValue === ”) {  //       return;  }     var getValue = g_form.getValue(“u_sts_user”);     if(!getValue){      g_form.setReadOnly(“u_sts_mode”, true)      g_form.setReadOnly(“u_requirements”, true)      g_form.setReadOnly(“u_sts_user_comment”, true)      g_form.showFieldMsg(“u_sts_user”, “Select User First”, “info”);     }     else{      g_form.setReadOnly(“u_sts_mode”, false)      g_form.setReadOnly(“u_requirements”, false)      g_form.setReadOnly(“u_sts_user_comment”, false)      g_form.hideFieldMsg(“u_sts_user”, true);     }  }  In this script, the “isLoading” check is commented out, allowing the onChange Client Script to run during form load. When the form initializes, ServiceNow sets the value of “u_sts_user”, which triggers the script and locks related fields until a user is selected. This ensures the form remains controlled both on load and during user interaction. 1.2 Summary: onChange Client Scripts make ServiceNow forms more interactive by responding immediately to field value changes. In some cases, these scripts also run during form load because field values are initialized in the background. Understanding the role of the isLoading parameter helps maintain predictable behavior and ensures a clean, well-controlled form experience. 

Dependent Choice Field in ServiceNow What is choice field? A Choice field is a predefined dropdown list that restricts user input to specific allowed values. These choices are stored in the sys_choice table.  What is a Dependent Choice Field? Dependent Choice fields change their values based on another field.  Scenario: – A college management system wants to store student details. While creating a student record, the user should first select the State, and based on the selected state, only the relevant districts should appear in the district dropdown.  Steps For Dependent Choice Field? Open instance  System Definition > Tables  Create new table with fields: –  Name(String)  Rollno(String)  State(Choice)  District(Choice)  Right click on state > configure dictionary > choices related list > New > Add choices.                                                                                             Choice  Dependent Value  Maharashtra  MH  Rajasthan  RJ  Gujrat  GJ   Submit.  Right click on District > configure dictionary > choices related list > New > Add choices    Choice  Value  Sequence  Dependent value  Mumbai  Mumbai  1  MH  Latur  Latur  2  MH  Raipur  Raipur  1  RJ  Kota  Kota  2  RJ  Surat  Surat  1  GJ  Baroda  Baroda  2  GJ  Advance view > Dependent field > click on use Dependent field > from dropdown select Dependent field (state) > submit > check results.  Dependent Choice filled created successfully.  Conclusion: – Choice fields are essential in ServiceNow development because they help maintain structured and consistent data. They are widely used in Incident, Change, Problem, and custom applications. Understanding choice fields is important for both ServiceNow developers and administrators.