Onload Client Script in servicenow

Client-side scripts execute within a user’s browser and are used to manage forms and form fields. Examples of things client-side scripts can do include:

• • • Place the cursor in a form field on form load
    • Generate alerts, confirmations, and messages
    • Populate a form field in response to another field’s value
    • Highlight a form field
    • Validate form data
    • Modify choice list options
    • Hide/Show fields or sections

How Onload client script works?

• • • Onload client script will execute once forms are loaded.
    • Script will get executed when the system first renders the form and before users can input the data.
    • Its been used when you want to change something on the form while it is loading.
    • Typically, onLoad()client scripts perform client-side-manipulation of the current form or set default record values.
    • Default code that system provides after select client script type as onload.

      function onLoad() {
         //Type appropriate comment here, and begin script below
         
      }

       

I have explained the above pic in details in the video. Request you to watch it for better understanding.

Now lets take a look on real word example

Real World Scenario

Requirement: Hide “Closed” Incident state and State from everyone accept user who has itil_admin role.

Solution: create onload client script and write below code.

function onload() {
    if (g_user.hasrole('itil_admin'))
        return;

    if (g_form.getvalue('incident_state') != '7')
        g_form.removeoption('incident_state', 7);
    if (g_form.getvalue('state') != '7')
        g_form.removeoption('state', 7);
}

Q. How can we change onChange client script into onLoad?

Ans: You need to do one simple change in if condition, just remove the “isLoading ||”

• • Default code for onchange

    function onChange(control, oldValue, newValue, isLoading, isTemplate) {
       if (isLoading || newValue === '') {
          return;
       }
    
       //Type appropriate comment here, and begin script below
       
    }

  • After removing “isLoading ||”, your base code looks like.

    function onChange(control, oldValue, newValue, isLoading, isTemplate) {
       if (newValue === '') {
          return;
       }
    
       //Type appropriate comment here, and begin script below
       
    }