javascript - How to save the subtracted value from span to cookie till checkbox unchecked -

i have bit of code carries numeric values within span when u click on checkbox subtract 1 main value, subtracts 1 total value, how achieve if form submitted deducted value in span remains same unless checkbox unchecked?

html here 10 example value:

<input type="checkbox" id="featured" name="featured" <?php echo $checked;?> /> (<span id="credit">10</span>) 

js:

<script> $(function () {   $('#featured').change(function () {     var currentvalue = parseint($('#credit').text());     var newvalue = currentvalue + ($(this).prop('checked') ? -1 : 1);     $('#credit').text(newvalue);   }); }); </script> 

your time , appreciated.

<script> $(function () {   $('#featured').change(function () {     var savedvalue = localstorage.checkboxvalue;     var currentvalue = savedvalue ? parseint(savedvalue) : parseint($('#credit').text());     var newvalue = currentvalue + ($(this).prop('checked') ? -1 : 1);     $('#credit').text(newvalue);     localstorage.checkboxvalue = newvalue;   }); }); </script>