how to fetch data from json in javascript.....

check the fallowing code

 $('#Fk_ProductSubGroupId').combobox({
        select: function () {
            //alert(this.value);
            // event.preventDefault();
            // var value;
            $('#Fk_ProductId').empty();
            $.ajax({
                url: '/Invoice/GetProducts',
                type: 'POST',
                dataType: 'json',
                data: { id: this.value },
                success: function (data) {
                    var i = 0;
                    while (data[i]) {
                        var option = $("" + data[i].Text + "");
                        $("#Fk_ProductId").append(option);
                        i++;
                    }
                    $('#Fk_ProductId').next().find('input').focus();
                },
                error: function () {
                    alert('error');
                }
            });
        }
    });

Hi Amit,

Please have a look at following links once:

https://www.dartlang.org/docs/tutorials/fetchdata/ 
http://api.jquery.com/jquery.getjson/