jQuery disable/enable submit button

I have this HTML:

<input type="text" name="textField" />
<input type="submit" value="send" />

How can I do something like this:

• When the text field is empty the submit should be disabled (disabled="disabled").
• When something is typed in the text field to remove the disabled attribute.
• If the text field becomes empty again(the text is deleted) the submit button should be disabled again.

I tried something like this:

$(document).ready(function(){
    $('input[type="submit"]').attr('disabled','disabled');
    $('input[type="text"]').change(function(){
        if($(this).val != ''){
            $('input[type="submit"]').removeAttr('disabled');
        }
    });
});

…but it doesn't work. Any ideas?