gistfile1.txt

function AuthFailed(msg){
  this.name = 'AuthFailed';
  this.message = msg;
  Error.call(this, msg);
  Error.captureStackTrace(this, arguments.callee);
}

AuthFailed.prototype.__proto__ = Error.prototype;

var err = new AuthFailed('test error');

console.log(err instanceof AuthFailed);