Magento - Difference between validator and validator.validate()

Question

In the login.phtml, what is the difference between validator and validate - Could someone explain what is the meaning of each of the lines below

function onepageLogin(button)
        {
            if(loginForm.validator && loginForm.validator.validate()){
                button.disabled = true;
                loginForm.submit();
            }
        }

Thanks.

Answer 1

loginForm.validator just checks the existence of the object (go on if it exists) and loginForm.validator.validate() calls the function validate() of the object (and if the function returns true, too, then the commands inside the if-clause will be executed).