Assuming the database name of the ServiceType field is "u_servicetype", this should work: var gr = new GlideRecord('sys_user');
gr.get(g_user.userID);
var svcType = gr.u_serviceType;

Note that this might have a slight UI delay since gr.get is doing synchronous AJAX call. You can do it asynchronously with a gr.query and a callback function, as:

var gr = new GlideRecord('sys_user');
gr.addQuery('sys_id',g_user.userID);
gr.query(function(user){
if(user.u_servicetype=="CMS"){
   return;
} else {
   // all the rest of your code...
}
});

BY Best Interview Question ON 26 Nov 2020