Mastering ServiceNow Scripting: Tips, Tricks, and Best Practices

ServiceNow is a powerful platform that enables organizations to streamline their workflows, automate processes, and drive digital transformation. As a ServiceNow developer or consultant, mastering the art of scripting is essential to unlock the full potential of the platform. In this blog post, we'll explore the world of ServiceNow scripting, providing you with valuable insights, tips, and best practices to take your skills to the next level.

Understanding the Programming Styles in ServiceNow

ServiceNow offers two primary programming styles:

1. Declarative Programming: This is the "low-code" or "no-code" approach to programming in ServiceNow. It involves using pre-built components, such as workflow, declarative business rules, and matching rules, to define the logic of your application without writing extensive code. Declarative programming is ideal for simple tasks and is widely used in ServiceNow.
2. Programmatic Scripting: When declarative programming falls short, you can resort to scripting to tackle more complex scenarios. ServiceNow scripting primarily uses JavaScript, but it also incorporates other technologies like AngularJS, jQuery, Node.js, Bootstrap, ECMAScript, HTML/CSS, Apache Jelly. Scripting allows you to customize and extend the functionality of ServiceNow beyond the limitations of declarative programming.

Mastering ServiceNow Scripting: Test Your Skills

To become proficient in ServiceNow scripting, it's crucial to understand and practice various scripting concepts. Let's dive into some example scripts and explanations to help you grasp the fundamentals:

1. Client Scripts: Client scripts are executed on the client-side and can be used to modify form behavior, validate data, and interact with the user interface. For example, a client script can set the assigned_to field to the logged-in user when the incident state is changed to 2 and the user has the ITIL role.

function onChange(control, oldValue, newValue, isLoading) {  if (!isLoading && newValue !== "") {    if (newValue === "2") {      var isItil = g_user.hasRole("itil");      if (isItil) {        g_form.setValue("assigned_to", g_user.userID);      }    }  }}

2. GlideRecord Scripts: GlideRecord is a server-side API that allows you to query and manipulate records in ServiceNow. It provides methods like addQuery, setLimit, and query to retrieve records based on specific criteria. GlideRecord scripts are commonly used in background scripts, business rules, and other server-side contexts.

(function () {  var grIncident = new GlideRecord("incident");  grIncident.addQuery("priority", "1");  grIncident.addQuery("state", "1");  grIncident.query();  while (grIncident.next()) {    gs.log("Incident Found: " + grIncident.number);  }})();

3. Encoded Queries: Encoded queries offer an alternative way to write query statements in ServiceNow. They use a special syntax to define the query conditions and can be more concise than traditional query methods. However, encoded queries may not be applicable in all situations.

(function () {  var grIncident = new GlideRecord("incident");  grIncident.addEncodedQuery("priority=1^state=1");  grIncident.query();  while (grIncident.next()) {    gs.log("Incident Found: " + grIncident.number);  }})();

4. Business Rules: Business rules are server-side scripts that are triggered based on specific conditions and can be used to automate processes, enforce business logic, and modify record data. For example, a business rule can create an outage record from an incident when a CI is added to the incident.

(function executeRule(current, previous) {  if (    (current.isValidRecord() &&      !current.cmdb_ci.nil() &&      previous.cmdb_ci.nil()) ||    current.cmdb_ci != previous.cmdb_ci  ) {    var ciOutage = new GlideRecord("cmdb_ci_outage");    ciOutage.initialize();    ciOutage.begin = current.opened_at;    ciOutage.end = current.closed_at;    ciOutage.cmdb_ci = current.cmdb_ci;    ciOutage.u_related_incident = current.sys_id;    ciOutage.type = "Outage";    ciOutage.insert();  }})(current, previous);

5. UI Actions: UI actions are scripts that are triggered from the user interface, such as form context menus or form links. They allow you to perform custom actions, navigate to different records, or execute specific functionality. For example, a UI action can convert an incident into a story or copy a contract record.

function createStory() {  var grStory = new GlideRecord("rm_story");  grStory.initialize();  grStory.short_description = current.short_description;  grStory.u_requestor = current.caller_id;  grStory.comments = current.comments.getJournalEntry(1);  grStory.work_notes = "Generated from Incident " + current.number;  var sysID = grStory.insert();  action.setRedirectURL(grStory);  action.setReturnURL(current);  current.close_code = "Moved to Story";  current.close_notes = "Moved to Story " + grStory.number;  current.state = 7;  current.active = false;  current.update();}

6. Workflow Scripts: Workflow scripts are used within the workflow engine to define custom logic and conditions. They can be used to make decisions, manipulate data, and control the flow of the workflow. For example, a workflow script can check if the manager of a requested item is the same as the person who opened the request.

function checkIfSame() {  if (current.variables.u_requested_for.manager == current.opened_by) {    return "yes";  }  return "no";}

7. UI Macros: UI macros are scripts that can be embedded in forms and UI pages to extend the user interface and add custom functionality. They are written using a combination of XML, JavaScript, and ServiceNow-specific tags. For example, a UI macro can add a button next to a field to show related incidents.

<?xml version="1.0" encoding="utf-8" ?><j:jelly trim="false" xmlns:j="jelly:core" xmlns:g="glide" xmlns:j2="null" xmlns:g2="null">   <g:evaluate var="jvar_guid" expression="gs.generateGUID(this);" />   <g:reference_decoration id="$" field="$"      onclick="showRelatedList('$'); "      title="${gs.getMessage('Show related incidents')}" image="images/icons/tasks.gifx"/>   <script>      function showRelatedList(reference) {         var s = reference.split('.');         var referenceField = s[s.length - 1];         var v = g_form.getValue(reference);         var w = new GlideDialogWindow('show_list');         w.setTitle('Related incidents');         w.setPreference('table', 'incident_list');         w.setPreference('sysparm_view', 'default');         w.setPreference('sysparm_query', referenceField + '=' + v);         w.render();      }   </script></j:jelly>

8. GlideAggregate Scripts: GlideAggregate is a server-side API that allows you to perform aggregate queries and calculations on large datasets. It is more efficient than using GlideRecord for certain types of queries, such as finding duplicates or calculating totals. For example, a GlideAggregate script can find all duplicate servers by IP address.

function getDuplicates(tablename, val) {  var dupRecords = [];  var gaDupCheck = new GlideAggregate(tablename);  gaDupCheck.addQuery("active", "true");  gaDupCheck.addAggregate("COUNT", val);  gaDupCheck.addNotNullQuery(val);  gaDupCheck.groupBy(val);  gaDupCheck.addHaving("COUNT", ">", 1);  gaDupCheck.query();  while (gaDupCheck.next()) {    dupRecords.push(gaDupCheck[val]);  }  return dupRecords;}

Best Practices for ServiceNow Scripting

To ensure the quality, performance, and maintainability of your ServiceNow scripts, consider the following best practices:

1. Follow Coding Standards: Adhere to consistent coding standards and conventions to improve code readability and maintainability. Use meaningful variable and function names, indent your code properly, and add comments to explain complex logic.
2. Optimize Performance: Be mindful of script performance, especially when dealing with large datasets. Use efficient querying techniques, limit the number of records retrieved, and avoid unnecessary loops or calculations. Utilize GlideAggregate for aggregate queries and calculations.
3. Implement Error Handling: Include error handling mechanisms in your scripts to gracefully handle exceptions, log errors, and provide meaningful error messages to users or administrators. This helps in identifying and resolving issues quickly.

try {  // Your script logic here} catch (error) {  gs.error("An error occurred: " + error.message);  // Handle the error gracefully}

4. Test Thoroughly: Thoroughly test your scripts to ensure they function as expected and handle various scenarios. Use the ServiceNow script debugger to step through your code, inspect variables, and identify any issues or bugs.
5. Document Your Code: Provide clear and concise documentation for your scripts, including the purpose, input/output parameters, and any dependencies. This helps other developers understand and maintain your code effectively.

/** * Retrieves duplicate records based on a specified field. * @param {string} tablename - The name of the table to check for duplicates. * @param {string} val - The field to check for duplicates. * @returns {Array} An array of duplicate values. */function getDuplicates(tablename, val) {  // Function implementation here}

6. Leverage Reusable Code: Identify common functionalities and create reusable scripts, such as script includes or library functions. This promotes code reuse, reduces duplication, and improves maintainability.
7. Stay Updated: Keep yourself updated with the latest ServiceNow releases, features, and best practices. Attend training sessions, workshops, and conferences to enhance your knowledge and stay ahead of the curve.

Conclusion

ServiceNow scripting is a powerful tool that allows you to customize and extend the capabilities of the platform. By understanding the different programming styles, practicing various scripting techniques, and following best practices, you can become a proficient ServiceNow developer and deliver high-quality solutions.

Remember, the key to mastering ServiceNow scripting is continuous learning and practice. Experiment with different scripts, explore the ServiceNow documentation, and engage with the community to expand your knowledge and skills.

Happy scripting!