SharePoint - JS to access Permission Groups

You may simplify the code from the given page, especially createDelegate method which you have problem with. The code is:

var clientContext = new SP.ClientContext.get_current()
var collGroup = clientContext.get_web().get_siteGroups();
var oGroup = collGroup.getById(111)
var userCreationInfo = new SP.UserCreationInformation();
userCreationInfo.set_loginName('DOMAIN\\alias');
this.oUser = oGroup.get_users().add(userCreationInfo);
clientContext.load(oUser);
clientContext.executeQueryAsync(
  function() { console.log('OK') },
  function(sender, args) { console.log('Request failed. ' + args.get_message() + '\n' + args.get_stackTrace()) }
);

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Note that there is no need to supply url, email and user name. Ensure double backslash in user login. Also - switch your SharePoint to debug mode: in web.config find <compilation batch="false" debug="false"> node and change it to <compilation batch="false" debug="true">. Perhaps it will produce more readable error messages.

Thanks - I only have FC - not farm access
Regardless, I need code to add and delete a user from a group -
is it simply    .delete.(userCreationInfo).

also have you actually run this successfully ?
Where is this kind of interface documented (for example, to see all users of a group).  thanks