Source code : สำหรับหาช่วงวัน-เวลา ซ้ำกัน ในแต่ละแถว

 <script type="text/javascript">  
 // Use iso8601 like datestring to make a local date object</font>  
 function getDateObj(s) {  
   var bits = s.split(/[- :]/);  
   var date = new Date(bits[0], bits[1] - 1, bits[2]);  
   date.setHours(bits[3], bits[4], 0);  
   return date;  
 }  
 var events = [  
   {id: 1, start: getDateObj('2014-05-1 15:00'), end: getDateObj('2014-05-2 03:00')},   
   {id: 2, start: getDateObj('2014-05-1 07:00'), end: getDateObj('2014-05-2 11:00')},   
   {id: 3, start: getDateObj('2014-05-5 18:20'), end: getDateObj('2014-05-5 23:00')},   
   {id: 4, start: getDateObj('2014-05-4 23:00'), end: getDateObj('2014-05-5 20:00')},   
   {id: 5, start: getDateObj('2014-05-3 20:00'), end: getDateObj('2014-05-3 22:00')}  
 ];  
 function getOverlappingEvents(eventArray) {  
   var result = [];  
   var a, b;  
   // Sort the event array on start time  
   eventArray.sort(function(a, b) {  
       return a.start - b.start;  
     });  
   // Get overlapping events  
   for (var i=0, iLen=eventArray.length - 1; i<iLen; i++) {  
     a = eventArray[i];  
     b = eventArray[i + 1];  
     if ((a.start <= b.start && a.end > b.start) ||  
         (a.start < b.end && a.end >= b.end) ) {  
        result.push([a.id, b.id]);  
     }  
   }  
   return result;  
 }  
 // Run it      
 alert(getOverlappingEvents(events).join('\n')); // 1,3 2,3 5,6  
 //</script>  

Big thank : http://codeformatter.blogspot.com/