Field script use cases

  • Release version: Xanadu
  • Updated July 31, 2025
  • 4 minutes to read
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    Summary of Field script use cases

    This guide presents practical examples of field customization scripts in ServiceNow, illustrating how client and server scripts can enhance form functionality and data integrity. These scripts are designed for specific use cases such as auto-populating fields, modifying field behavior, and managing date/time values. Note that these scripts are provided as-is, without official Now Support, and should be tested extensively before production use.

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    Key Use Cases and Examples

    • Automatically Populate a Field: A client script auto-fills the Short Description on the Incident form based on the selected Subcategory. It queries a lookup table to set the appropriate description dynamically when the subcategory changes.
    • Disable HTML Tags in Descriptions: Server-side script replaces HTML <script> tags with non-executing text in both Description and Short Description fields to prevent script injection.
    • Trim Leading and Trailing Spaces: A script iterates over user records to remove unnecessary spaces from the FirstName and LastName fields, ensuring clean data.
    • Make Field Label Flash: Client script example to visually highlight a field label (e.g., Incident Number) by flashing it with a specified color for a defined duration.
    • Make Field Label Bold: Client script to set a field label’s font weight to bold, exemplified with the Incident Short Description field.
    • Make Fields Read-Only: OnLoad client script locks down several Incident fields (such as Incident State, Impact, Urgency, Priority, Configuration Item, and Assigned To) based on Incident State values, also removing lookup icons from reference fields.
    • Set Current Date/Time in a Field: Combines client-side GlideAjax with a server-side Script Include to set the current date/time in a date/time field, handling proper formatting and timezone considerations.
    • Toggle Timer Field by Field Name: Client script that toggles the state of a timer widget associated with a specified field name, simulating user interactions to pause or start the timer.
    • Modify GlideDateTime Field Value: Server-side script utilizing the GlideDateTime API to add or subtract time intervals (seconds, days, weeks, months, years) from date/time fields, with support for local and UTC time zones.

    Practical Considerations for ServiceNow Customers

    • These scripts enable automation and enhanced user experience by dynamically updating fields and controlling form behavior.
    • They help maintain data quality by sanitizing inputs and trimming unwanted spaces.
    • The examples demonstrate both client-side and server-side scripting techniques suited for common customization scenarios.
    • Using GlideAjax bridges client and server scripts, allowing accurate setting of date/time values respecting time zones.
    • All customizations should be thoroughly tested in your instance environment before deployment to ensure compatibility and performance.
    • For community support and further questions, customers are encouraged to engage with the ServiceNow community forums.

    Common use cases for field customization scripts.

    Warning:
    The customization described here was developed for use in specific instances, and is not supported by Now Support. This method is provided as-is and should be tested thoroughly before implementation. Post all questions and comments regarding this customization to our community forum.

    For more information, see Server API reference.

    Automatically populate a field

    The following example shows how to use a client script to auto-fill a Short Description based on the selected Subcategory.

    In this case, if the table has a record with Subcategory = Password and Short Description = Password Reset. When the user selects the Subcategory of Password on the Incident form, a client script looks up the matching record and sets Short Description equal to Password Reset.

    Client script settings:
    • Type = onChange
    • Table name = incident
    • Field name = Subcategory
    function onChange(control, oldValue, newValue, isLoading){
    if(isLoading){return;}
    var newrec = gel('sys_row');
    //Check if new record
    if (newrec.value == -1) {
        var lookup = new GlideRecord('u_short_desc_lookup');
        lookup.addQuery('u_subcategory', g_form.getValue('subcategory'));
        lookup.query();
        var temp; //temp var - reusable
        if(lookup.next()){
            temp = lookup.u_short_description;
            if(null != temp) {
                //Set the form value from lookup if there is a lookup value
                g_form.setValue('short_description', temp);
            } else {
                g_form.setValue('short_description',"");
                }
          } else {
              //If a lookup record does not exist based on lookup.addQuery
              //Then set to UNDEFINED or NULL depending on type
              g_form.setValue('short_description',"");
              }
     }
}

    Disable HTML tags in descriptions

    This code disables HTML tags in Description and Short Description fields by substituting the tags with non-executing versions. 
    doit();
 
function doit(){ 
 var desc = current.description.toString();
 var shdesc = current.short_description.toString();
 if(desc.indexOf('script>')>-1|| shdesc.indexOf('script>')>-1){
   desc = desc.replace(/<script>/g,"(script)");
   current.description = desc.replace(/<\/script>/g,"(\/script)");
   shdesc = shdesc.replace(/<script>/g,"(script)");
   current.short_description = shdesc.replace(/<\/script>/g,"(\/script)");}
}

    Eliminate leading and trailing spaces in fields

    This example of the script trims trailing and leading spaces in the FirstName and LastName fields of the sys_user. 
    doit();
 
function doit(){ 
  var now_GR =new GlideRecord('sys_user');
  gr.query();
  while(gr.next()){
    if((gr.first_name.toString().length!= gr.first_name.toString().trim().length)||(gr.last_name.toString().length!= gr.last_name.toString().trim().length)){
     gr.first_name= gr.first_name.toString().trim();
     gr.last_name= gr.last_name.toString().trim();
     gr.autoSysFields(false);
     gr.update();}}
}

    Make a field label flash

    The following client script example is for the number field on incident. The label flashes for two seconds.
    g_form.flash("incident.number","#FFFACD",0);
    The arguments for the flash method are as follows:
    • tablename.fieldname
    • RGB color or acceptable CSS color like "blue" or "tomato"
    • Integer that determines how long the label flashes:
      • 2 for a 1-second flash
      • 0 for a 2-second flash
      • -2 for a 3-second flash
      • -4 for a 4-second flash
    Note:
    Do not specify this argument if you want the field label colored the specified color.

    Make a field label bold

    This client script makes the label of a particular field bold. In this case, the field is the Short Description on the Incident Table. 
    function onLoad(){
  var l = g_form.getLabel('incident.short_description');
  l.style.fontWeight = 'bold';}

    Make fields read-only

    This onLoad client script makes the following fields on the Incident [incident] table read-only:
    • Incident state
    • Impact
    • Urgency
    • Priority
    • Configuration item
    • Assigned to
    The script also removes the magnifying glass for the read-only Reference Fields (Configuration item and Assigned to). 
    function onLoad(){
var incidentState = g_form.getValue('incident_state');
if( incidentState == '6'|| incidentState == '7'){
   g_form.setReadonly('incident_state',true);
   g_form.setReadonly('impact',true);
   g_form.setReadonly('urgency',true);
   g_form.setReadonly('priority',true);
   g_form.setReadonly('cmdb_ci',true);
   g_form.setReadonly('assigned_to',true);}}

    Set current date/time in field

    You can set date and time values in client scripts and script includes.

    Client script
    You can use the following two lines to set the current date and time in a date/time field. This approach bypasses the problem of getting the value into the proper format and proper time zone.
    var ajax = new GlideAjax('MyDateTimeAjax');
  ajax.addParam('sysparm_name','nowDateTime');
  ajax.getXML(function(){
    g_form.setValue('put your field name here', ajax.getAnswer());});
    For more information on running server-side scripts with the client, refer to GlideAjax.
    System script include
    // Be sure the Glide AJAX enabled option is checked
 
var MyDateTimeAjax = Class.create();
MyDateTimeAjax.prototype = Object.extendsObject(AbstractAjaxProcessor,{
  nowDateTime:function(){
    return gs.nowDateTime();}});

    Toggle the timer field by field name

    The following client script toggles the timer field based on a particular field name. 
    function toggleTimerByFieldName(fieldName){
 //Step 1: Find the timer object
 //timeObjectName: the timer objects name as it would normally be referenced
 //timeObjectHidden: the hidden input node in the field td
 //timeObjectParent: the parent td node containing the field and it's constituent nodes
 //timeObjectFields: anchor tag with onclick to stop timer
 
 var timeObjectName = fieldName;
 var timeObjectHidden = gel(timeObjectName);
 
 //Step 2: simulate click stop button
 var timeObjectParent;
 var timeObjectFields;
 
 //verify that we got the correct object
 if(timeObjectHidden.type=="hidden"){
 
    //Get Parent td node
    timeObjectParent = timeObjectHidden.parentNode;
 
    //Get input fields
    timeObjectFields = timeObjectParent.getElementsByTagName("input");
 
    //simulate click of stop button
    var timerTestString ="paused";
    var timerImg;
 
    //loop through input objects looking for the pause timer object
    for(var elIt=0; elIt < timeObjectFields.length; elIt++){
      if(timeObjectFields[elIt].id.match(timerTestString)){
        if(timeObjectFields[elIt].value=="false"){
          timeObjectFields[elIt].value="true";
          timerImg = timeObjectParent.getElementsByTagName("img")[0];
          timerImg.src="images/timer_start.gifx";}
      elseif(timeObjectFields[elIt].value=="true"){
          timeObjectFields[elIt].value="false";
          timerImg = timeObjectParent.getElementsByTagName("img")[0];
          timerImg.src="images/timer_stop.gifx";}}}}}

    Modify GlideDateTime field value

    The following example uses a server-side script to access a GlideDateTime field.

    The following server-side script example shows how to modify values using the GlideDateTime API. The same concept also applies to the GlideDate object. 
    //You first need a GlideDateTime object
//this can be from instantiating a new object "var gdt = new GlideDateTime()"
//or getting the object from a GlideDateTime field
//getting the field value (for example: var gdt = current.start_date) 
//only returns the string value, not the object
//to get the object use var gdt = current.start_date.getGlideObject();
//now gdt is a GlideDateTime object
var gdt = current.start_date.getGlideObject();
 
//All methods can use negative values to subtract intervals
 
//add 1 hour (60 mins * 60 secs)
gdt.addSecondsLocalTime(3600);
 
//add 1 day
gdt.addDaysLocalTime(1);
 
//subtract 1 day
gdt.addDaysLocalTime(-1);
 
//add 3 weeks
gdt.addWeeksLocalTime(3);
 
//subtract 6 months.
gdt.addMonthsLocalTime(-6);
 
//add 1 year, representing the date and time using the UTC timezone instead of the local user's timezone.
gdt.addYearsUTC(1);