Field script use cases

  • Release version: Yokohama
  • Updated March 12, 2026
  • 3 minutes to read
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    Summary of Field script use cases

    This content provides practical examples of client and server-side scripts to customize fields in ServiceNow, specifically in the Yokohama release. These scripts enable automation, data integrity, UI enhancements, and field behavior control. The examples are designed for specific scenarios and require thorough testing before deployment, as they are unsupported by Now Support.

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    Common Use Cases and Examples

    • Auto-populate a field: Using an onChange client script on the Incident table’s Subcategory field to automatically set the Short Description by looking up a matching record.
    • Disable HTML tags in text fields: Server-side script example that replaces <script> tags in Description and Short Description fields with non-executing text to prevent script injection.
    • Trim leading and trailing spaces: Server-side script that iterates through sysuser records to remove unwanted spaces in First Name and Last Name fields, ensuring cleaner data.
    • Make a field label flash or bold: Client scripts to visually draw attention to fields by flashing the label with configurable colors and duration or by making the label text bold.
    • Make fields read-only: Client script example that sets multiple Incident fields as read-only based on the Incident state, also removing search icons from reference fields to reflect their read-only status.
    • Set current date/time in a field: Use of GlideAjax and a server-side script include to set date/time values correctly formatted and timezone-aware in client scripts.
    • Toggle timer field by field name: Client script to programmatically start or stop timer fields by simulating user interaction, useful for time tracking controls.

    Practical Benefits for ServiceNow Customers

    • Increased efficiency: Automate field population and formatting to reduce manual entry and errors.
    • Improved data quality: Enforce data consistency through trimming and HTML sanitization scripts.
    • Enhanced user experience: Use visual cues like flashing or bold labels to highlight important fields.
    • Controlled field behavior: Make fields read-only based on business logic to prevent unauthorized changes.
    • Accurate date/time handling: Ensure reliable date/time inputs in client forms using server-side processing.
    • Custom timer control: Enable programmatic control over timer fields to support precise time tracking workflows.

    Important Considerations

    These scripts are provided “as-is” for specific use cases and are not officially supported. Customers should test extensively in their own environments and use the ServiceNow community for questions or feedback. Understanding the underlying APIs such as GlideRecord, GlideAjax, and client scripting methods is essential for successful implementation.

    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 values