What is g_user #

g_user is used pretty heavily to control access and other things in
Servicenow. I go over all the methods and properties of those below.

firstName #

The current user's first name.

 console.log('first name = ' + g_user.firstName);

getClientData #

Gets a session client value previously set with putClientData().

Session client data is a set of named strings that may be setup on the
server (using putClientData()) that then may be used by client scripts
(using getClientData()). Can be used during form load time to get
information that the client script needs to make decisions about the
form, for example, which fields should be visible.

 var loginLanguage = g_user.getClientData("loginlanguage");

getFullName #

Returns the first and last name of the current user.

 var formalName = g_user.getFullName();

hasRole #

Returns true if the current user has the specified or admin role.

 var isAdmin = g_user.hasRole('admin');

hasRoleExactly #

Returns true only if the current user has the specified role.

 var isItil = g_user.hasRoleExactly('itil');

hasRoleFromList #

Returns true if the current user has at least one of the specified roles
or has the admin role.

 var isOK = g_user.hasRoleFromList("itil, maint");

hasRoles #

Returns true if the current user has any role.

 var yesRole = g_user.hasRoles();

lastName #

The current user's last name.

 console.log('last name = ' + g_user.lastName);

userID #

The sys_id of the current user.

 var userID = g_user.userID;
console.log('Current user ID = ' + userID);

userName #

This property is the current user's username, for example gsmith02. It
is not the user's name, for example George Smith.

 var userName = g_user.userName;
console.log('Current user = ' + userName);