Require attachment for catalog item in Platform and Service Portal

Follow the below steps:-

1.Create UI Script

UI Script: GlobalCatalogItemFunctions

Global: true

Script:

function getSCAttachmentCount() {

   var length;

   try {

   length = angular.element("#sc_cat_item").scope().attachments.length;

   } catch(e) {

   length = -1;

   }

   return length;

}

2. Select your Portal > Theme(Open the theme and go to the related list section, click JS include tab and click the new UI action). 

Create New:- JS Theme

Display Name:- GlobalCatalogItemFunctions

Source:- UI Script

UI Script: GlobalCatalogItemFunctions(Select the UI script that is you created)

3. Catalog Client Script:

function onSubmit() {

   //Works in non-portal UI

   try {

   var attachments = document.getElementById('header_attachment_list_label');

   if (attachments.style.visibility == 'hidden' || attachments.style.display == 'none' ) {

   alert('You must attach the completed form before submitting this request.');

   return false;

   }

   }

   //For Service Portal

   catch(e) {

   var count = getSCAttachmentCount();

   if(count <= 0) {

   alert('You must attach the completed form before submitting this request.');

   return false;

   }

   }

}