Submitting a form on 'Enter' with jQuery?

Question

I have a bog-standard login form - an email text field, a password field and a submit button on an AIR project that\'s using HTML/jQuery. When I hit Enter on the form, the

Answer 1

In HTML codes:

    First Name: 
    

    Last Name: 
    

    

In Js codes:

function ajax_submit()
{
    $.ajax({
        url: "submit.php",
        type: "POST",
        data: {
            firstname: $("#firstname").val(),
            lastname: $("#lastname").val()
        },
        dataType: "JSON",
        success: function (jsonStr) {
            // another codes when result is success
        }
    });
}