disable submit button if inputs are empty with jQuery

Question

I'm attempting to disable a submit button untill the user has filled out the input fields in the form.

I found THIS thread here which had a really good answer. I'm having just a little problem getting the submit button the re-enable when the fields are filled out.

Can someone please take a look at this function and help me figure out what I'm missing? Any help would be greatly appreciated :D Thank you.

Heres a Fiddle also

$(document).ready(function() {
var $submit = $("input[type=submit]");

if ( $("input:empty").length > 0 ) {
$submit.attr("disabled","disabled");
} else {
$submit.removeAttr("disabled");
}
});


<form method="POST" action="<%=request.ServerVariables("SCRIPT_NAME")%>">
User Name: <input name="Username" type="text" size="14" maxlength="14" /><br />
Password: <input name="last_name" type="password" size="14" maxlength="14"><br />
<input type="submit" value="Login" name="Submit" id="loggy">
</form>

Answer 1

$(document).ready(function() {
    var $submit = $("input[type=submit]"),
        $inputs = $('input[type=text], input[type=password]');

    function checkEmpty() {

        // filter over the empty inputs

        return $inputs.filter(function() {
            return !$.trim(this.value);
        }).length === 0;
    }

    $inputs.on('blur', function() {
        $submit.prop("disabled", !checkEmpty());
    }).blur(); // trigger an initial blur
});

Working sample

Instead of blur you can also use keyup like:

    $inputs.on('keyup', function() {
        $submit.prop("disabled", !checkEmpty());
    }).keyup();  // trigger an initial keyup

Also you can combine multiple events:

    $inputs.on('keyup blur', function() {
        $submit.prop("disabled", !checkEmpty());
    }).keyup();  // trigger any one