As I see, it is a JavaScript timestamp.
Ok:
1352656800000
means
Sun, 11 Nov 2012 18:00:00 GMT
So, first of all decode the JSON string to an object. Than parse it and for every matching field (since you have not given the whole structure, you have to find them), use the following function (supposing, that the field value format is
/Date(1352656800000)/
):
<script>
function ParseDate(input){
theDate = new Date(parseInt(input.substring(6,19)));
return theDate.toGMTString();
}
alert(ParseDate("/Date(1352656800000)/"));
</script>
If you need formatting, or you have to use the timestamp as javascript date object, just change the returned expression.