Trigger Event when someone is added to a list

Business Rules/Trigger Event when a member is added to a list/Readme.md

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+Scenario: You are wanting to send a notification to someone whenever they are added to a list of people. 
+
+Application: Create an event in the event registry. Then, create a business rule. Set the name and table, advanced = true. 
+
+When to run: 
+When = after, update = true, conditions = watch list (replace with applicable field name) | changes
+
+Advanced tab: insert the snippet

Business Rules/Trigger Event when a member is added to a list/Trigger an event when user is added to field.js

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+(function executeRule(current, previous /*null when async*/) {
+
+    // Ensure the 'watch_list' (replace with applicable field name) field has been modified
+    if (current.watch_list != previous.watch_list) {
+
+        // Split the current and previous watch lists into arrays
+        var newWatchers = current.watch_list.split(',');
+        var oldWatchers = previous.watch_list ? previous.watch_list.split(',') : [];
+
+        // Identify the newly added users to the watch list
+        var addedUsers = newWatchers.filter(function (user) {
+            return oldWatchers.indexOf(user) === -1;
+        });
+
+        // Loop through the added users to trigger the event for each
+        addedUsers.forEach(function(userID) {
+            var email;
+            var firstName;
+
+            // Try to get the user record by user ID (sys_id)
+            var userGr = new GlideRecord('sys_user');
+            if (userGr.get(userID)) {
+                firstName = userGr.first_name;
+                email = userGr.email;
+            } else {
+
+                // If no user record is found, assume the userID is an email address
+                email = userID;
+                firstName = "Team";
+            }
+
+            // Trigger the event (replace "new_member") with the current case and user information
+            gs.eventQueue('new_member', current, email, firstName);
+        });
+    }
+})(current, previous);