Concert - try

function concert(param){
    let obj = {};

    for(let el of param){
        if(el === 'start of concert'){
            break;
        }
        let [command,bandName,memberName] = el.split('; ');

        if(command === 'Play'){
            let time = +memberName;

            if(!obj[bandName]){
                obj[bandName] = {time};
            }else{
                obj[bandName].time += time;
            }


        }else if(command === 'Add'){
              let bandMembers = memberName.split(', ');
              let sortedBandMembers = sortMembers(bandMembers);

              if(!obj[bandName]){
                obj[bandName] = {};
                obj[bandName]  = {sortedBandMembers};//tuk se dobavqt 4lenovete na bandata i se zapazva time ako go ima
              }else{
                obj[bandName] = {sortedBandMembers};//tuk ako ima nov 4ovek v banda se dobava kum ostanallite
              }
        }
    }
    function sortMembers(arr){
       return arr.filter((el,ind)=> arr.indexOf(el) === ind)
    }
}
concert([

    'Play; The Beatles; 2000',
    'Add; The Beatles; John Lennon, Paul McCartney, George Harrison, Ringo Starr',
    'Add; The Beatles; Ivan, John Lennon, Paul McCartney, George Harrison, Ringo Starr',
    'Add; Eagles; Glenn Frey, Don Henley, Bernie Leadon, Randy Meisner',
    'Play; Eagles; 1869',
    'Add; The Rolling Stones; Brian Jones, Mick Jagger, Keith Richards',
    'Add; The Rolling Stones; Brian Jones, Mick Jagger, Keith Richards, Bill Wyman, Charlie Watts, Ian Stewart',
    'Play; The Rolling Stones; 4239',
    'start of concert',
    'The Rolling Stones'
  ]
  );