Example of Custom form calculation: 
                <-script type="text/javascript">

                    dhis2.util.on( 'dhis2.de.event.formReady', function( event,iReVg2xgFPL ) {
                          var periodN= $( '#selectedPeriodId' ).val();// From DHIS2 Selection Param
                          var nextPeriod=(+periodN) + (+1);//201611,201612,201613
                          var nextPeriodSeperate=periodN.toString().substring(0, 4);
                          var year=parseInt(nextPeriodSeperate.trim());
                          var month=parseInt(periodN % 100);
                          if(month==12){
                            year++;
                            month='01';
                            nextPeriod=year+'01';   
                            //console.log("Next period: "+nextPeriod);
                          } 
                         $('.selectedDate').val(nextPeriod);
                    });
                    function validateStockOutNumber(stockoutDays){
                        var sOut=$(stockoutDays).val();
                        if(sOut>31){
                          $(stockoutDays).val(' ');
                          $(stockoutDays).val(0);
                          alert('Sorry the number of stockout days can not be greater than 31 ');
                        }
                    }
                    function closingBL(op,re,adplus,adminus,con,closingid,opnextId,period){
                    // All id pick
                     var opbalance= new Number(document.getElementById(op).value);
                     var receipts= new Number(document.getElementById(re).value);
                     var adjustPlus= new Number(document.getElementById(adplus).value);
                     var adjustMinus= new Number(document.getElementById(adminus).value);
                     var consump= new Number(document.getElementById(con).value);
                     var nextPeriod= $(period).val();
                    // Closing Balance text data set
                    var clobalance=opbalance+receipts+adjustPlus-adjustMinus-consump;
                    $(closingid).val(clobalance);// Display closing balance at the text field
                    $(opnextId).val(clobalance);// Display closing balance at the text field
                    $(closingid).change();
                    $(opnextId).change();
                    $(closingid).prop("readonly",true);
                    $(opnextId).prop("readonly",true);
                    // Spliting Element ID
                    var ArrayFromString = op.split("-");
                    var elementId=ArrayFromString[0];

                    //console.log('Element Id: '+elementId);
                    //console.log('nextPeriod Id: '+nextPeriod);
                    var valueSaver = new ValueSaver( elementId,nextPeriod, 'dCWAvZ8hcrs', clobalance, null, 'red' );
                    valueSaver.save();

                    }
                    <-/script>
               

                

                
 Example of Custom form calculation: 
                <-script type="text/javascript">

                    dhis2.util.on( 'dhis2.de.event.formReady', function( event,iReVg2xgFPL ) {
                          var periodN= $( '#selectedPeriodId' ).val();// From DHIS2 Selection Param
                          var nextPeriod=(+periodN) + (+1);//201611,201612,201613
                          var nextPeriodSeperate=periodN.toString().substring(0, 4);
                          var year=parseInt(nextPeriodSeperate.trim());
                          var month=parseInt(periodN % 100);
                          if(month==12){
                            year++;
                            month='01';
                            nextPeriod=year+'01';   
                            //console.log("Next period: "+nextPeriod);
                          } 
                         $('.selectedDate').val(nextPeriod);
                    });
                    function validateStockOutNumber(stockoutDays){
                        var sOut=$(stockoutDays).val();
                        if(sOut>31){
                          $(stockoutDays).val(' ');
                          $(stockoutDays).val(0);
                          alert('Sorry the number of stockout days can not be greater than 31 ');
                        }
                    }
                    function closingBL(op,re,adplus,adminus,con,closingid,opnextId,period){
                    // All id pick
                     var opbalance= new Number(document.getElementById(op).value);
                     var receipts= new Number(document.getElementById(re).value);
                     var adjustPlus= new Number(document.getElementById(adplus).value);
                     var adjustMinus= new Number(document.getElementById(adminus).value);
                     var consump= new Number(document.getElementById(con).value);
                     var nextPeriod= $(period).val();
                    // Closing Balance text data set
                    var clobalance=opbalance+receipts+adjustPlus-adjustMinus-consump;
                    $(closingid).val(clobalance);// Display closing balance at the text field
                    $(opnextId).val(clobalance);// Display closing balance at the text field
                    $(closingid).change();
                    $(opnextId).change();
                    $(closingid).prop("readonly",true);
                    $(opnextId).prop("readonly",true);
                    // Spliting Element ID
                    var ArrayFromString = op.split("-");
                    var elementId=ArrayFromString[0];

                    //console.log('Element Id: '+elementId);
                    //console.log('nextPeriod Id: '+nextPeriod);
                    var valueSaver = new ValueSaver( elementId,nextPeriod, 'dCWAvZ8hcrs', clobalance, null, 'red' );
                    valueSaver.save();

                    }
                    <-/script>