在Ajax中，图像不能与其他表单数据一起上传，在$ _FILES中显示空白数组

I am trying to save image and other forms data with ajax, But Some problems facing while uploading image. Image is selected and Sent from js but in php $_FILES not getting this image its return blank

IN js

     var datastr = 'productionstrategyno='+productionstrategyno+
'&manufacturingleadtime='+manufacturingleadtime;
     if (($("#item-master-image"))[0].files.length > 0) {
                                    file = ($("#item-master-image"))[0].files[0];
                                    datastr += '&images='+file;
                                }

                                $.ajax({
                                url: base_url+'ajax_response/item_master',
                                type: 'post',
                                data: datastr,
                                dataType: 'json',
                                enctype: 'multipart/form-data',
                                processData: false,  // do not process the data as url encoded params
                                success: function(json) {

                                    if(json.status="200"){
                                        msgalert(json.msg,"success");
                                        window.location.href=base_url+"master/listItem";
                                    }else{
                                        msgalert(json.msg,"danger");

                                    }
                                }
                                });

It's send to php giving

isstandardmaterial:1
ismaintainbincard:1
images:[object File]

In PHP

<?php print_r($_FILES['images']); ?>

It return blank array value