Detecting Browser Autofill

Question

How do you tell if a browser has auto filled a text-box? Especially with username & password boxes that autofill around page load.

My first question is when does

Answer 1

I used the blur event on the username to check if the pwd field had been auto-filled.

 $('#userNameTextBox').blur(function () {
        if ($('#userNameTextBox').val() == "") {
            $('#userNameTextBox').val("User Name");
        }
        if ($('#passwordTextBox').val() != "") {
            $('#passwordTextBoxClear').hide(); // textbox with "Password" text in it
            $('#passwordTextBox').show();
        }
    });

This works for IE, and should work for all other browsers (I've only checked IE)