I am trying to make a class in javascript.

```
define(['knockout', 'knockout-validation', 'jquery'], function(ko, validation, $) {
    var SignUpViewModel = {
        name: ko.observable().extend({
            required: true
        }),
        email: ko.observable().extend({
            required: true,
            email: true
        }),
        password: ko.observable().extend({
            required: true
        }),
        confirmPassword: ko.observable().extend({
            areSame: {
                params: password,
                message: "Repeat password must match Password"
            }
        }), // this line contains error . 
        register: function() {}
    }
    return SignUpViewModel;
});

```

Now its giving `undefined` error at password 

Thanks in advance.