You need not do GlideRecord in that case. You can fetch the logged in user info at client side with help of g_user.
Please try with below script.
function onChange(control, oldValue, newValue, isLoading) {
if (isLoading || newValue == '') {
return;
}
var myself = g_form.getValue('voicemail_for_who');
var id = g_form.getValue('name');
alert(myself); //This is for testing purpose to check what value you get in myself variable.
if(myself == 'Myself') {
g_form.setValue('name', g_user.userID); //use this if name is a reference field
g_form.setValue('name', g_user.userName;); //use this line if name is a string field.
}
}
Reference:
GlideUser (g user) - ServiceNow Wiki
