Js Array: Tagging Duplicates

I have an array of objects like this ... [{ 'Event_code': 'AB-001', 'Interest_area': 'Arts', 'Start_time': '9:00 AM', 'End_time': '3:00 PM', 'Session_type': 'Co

Solution 1:

Use Array.forEach

Using if/else

var arr = [{"Event_code":"AB-001","Interest_area":"Arts","Start_time":"9:00 AM","End_time":"3:00 PM","Session_type":"Course information session"},{"Event_code":"AB-002","Interest_area":"Arts","Start_time":"12:30 PM","End_time":"1:00 PM","Session_type":"Course information session"},{"Event_code":"AB-003","Interest_area":"","Start_time":"9:00 AM","End_time":"3:00 PM","Session_type":"Course information session"},{"Event_code":"AB-004","Interest_area":"Business","Start_time":"10:30 AM","End_time":"11:00 AM","Session_type":"Course information session"},{"Event_code":"AB-005","Interest_area":"General Interest","Start_time":"9:00 AM","End_time":"1:30 PM","Session_type":"Experience"},{"Event_code":"AB-006","Interest_area":"Environment ,    Business       ","Start_time":"11:00 AM","End_time":"11:30 AM","Session_type":"Course information session"}];

var st = {};
arr.forEach(o => {
  if(st[o.Start_time]) o.clash = "yes";
  else st[o.Start_time] = o.Start_time;
});
console.log(arr);

Using Ternary Operator

var arr = [{"Event_code":"AB-001","Interest_area":"Arts","Start_time":"9:00 AM","End_time":"3:00 PM","Session_type":"Course information session"},{"Event_code":"AB-002","Interest_area":"Arts","Start_time":"12:30 PM","End_time":"1:00 PM","Session_type":"Course information session"},{"Event_code":"AB-003","Interest_area":"","Start_time":"9:00 AM","End_time":"3:00 PM","Session_type":"Course information session"},{"Event_code":"AB-004","Interest_area":"Business","Start_time":"10:30 AM","End_time":"11:00 AM","Session_type":"Course information session"},{"Event_code":"AB-005","Interest_area":"General Interest","Start_time":"9:00 AM","End_time":"1:30 PM","Session_type":"Experience"},{"Event_code":"AB-006","Interest_area":"Environment ,    Business       ","Start_time":"11:00 AM","End_time":"11:30 AM","Session_type":"Course information session"}];

var st = {};
arr.forEach(o => st[o.Start_time] ? o.clash = "yes": st[o.Start_time] = o.Start_time);
console.log(arr);