jquery uncheck checkbox problem

Question

i've got a checkbox, and an inputfield with a default value giving information about what to write into. if the checkbox is checked, the cursor should be on focus in the input field and it should be empty. if i uncheck the checkbox, the default value should be visible again.

that's my the checkbox code:

<input name="city" type="checkbox" id="checkcity"/> 
<input type="text" name="city" id="city" value="###VALUE_CITY###" />

and i've got the following jquery:

 var $city = $("input#city");
 var cityValue = "Your city...";

 !$city.val() && $city.val(cityValue);


  $('#checkcity').click(function(){
    if ($(this).is(':checked')) {
        $city.focus();
    } else {
        $city.val(cityValue);
        $(this).attr({checked: false}); 
    }
 });

//edit start i've got some more code, maybe the error is in this part (first i thought it's not relevant, but maybe it is, sorry)

this should do the following (what also works fine) when i click directly into the inputfield, checkbox is checked, when i leave it without content, checkbox is unchecked, default textvalue "your city..." is inside inputfield, when i enter some other text, checkbox is stilled checked. when i uncheck the box, default value is inside the inputfield. the only problem is, when inputfield is empty and i uncheck the checkbox... it won't work

  !$city.val() && $city.val(cityValue);
  $city.focus(function() { $city.val() == cityValue && $city.val("");$('#checkcity').attr({checked: true});});
  $city.blur(function() { 
        if ($city.val().length > 0 && $city.val() != cityValue){ 
            $('#checkcity').attr('checked', true);
            }                                                  
        if ($city.val() == "") {
            $('#checkcity').removeAttr('checked');
            $city.val(cityValue);
            }
        });

  $city.val() && $('#checkcity').attr('checked', true);
  $city.val() == cityValue && $('#checkcity').removeAttr('checked');

//edit end

It works fine, to check the box and set the cursor into input#city, but if i uncheck the box, it only works like it should as long as i press the left mousebutton down (box unchecked and default value in inputfield), but after the button goes up, the box is checked again und the inputfield is empty. When i uncheck the box and move the cursor during pressing down the left mousebutton out of the checkbox area, it also works fine.

Answer 1

If you are using jquery 1.6.0 or greater, replace

$(this).attr({checked: false});

with

$(this).prop("checked", false);

else, if you are using an older version of jquery, use

$(this).removeAttr("checked");

Answer 2

You dont have to set the checked property

Take a look at this http://jsfiddle.net/fxzD7/1/