Jquery Ajax Example

 $.ajax({
            type: 'GET',// you can use post also :P
            url: ajax.php, // your ajax controller file here 
            dataType: 'json',
            data: { firstcol: firstcol, secondcol: secondcol, thirdcol: thirdcol,id: id,updatecol:true },
            beforeSend: function () {
                // here we append a loading image
            },
            success: function (data) {
                // successful request; do something with the data
                console.log(data);
            },
            error: function () {
                // failed request;
            }
        });