Async calls inside "response"

My use case looks something like this:

'use strict';
	
	var _postLogin, _stubs;
	
	_stubs = myApp.stubs;
	
	_postLogin = $.mockjax({
		type : 'post',
		url : '/api/login',
		response : function (settings) {
			var _email, _passphrase, that;

			_email = settings.data.email;
			_passphrase = settings.data.passphrase;

			that = this;

			_stubs.db.login(_email, _passphrase, function (result) {

					that.responseText = result;
				
			});
}
});
	
_stubs.postLogin = _postLogin;