javascript操作json

for (var i = 0; i < selectedPartList.length; i++) {            if (selectedPartList[i].vpart_code == jsonRow.vpart_code) {                selectedPartList.splice(i, 1);//删除一项            }        }        if (quantity != "0") {            jsonRow.vused_qty = quantity;            selectedPartList.push(jsonRow);//添加一项        }