ecma - javascript using reduce function -

i have below array

 ["0,5,p1", "24,29,p2", "78,83,p2", "78,83,p3", "162,167,p2" ]  

i want output ["5,p1","10,p2","5,p3"] , p1..3 video files paying time start , end time . 0,5 mean p1 profile played 5 sec , on. want know profile take time in total using ecma script map,reduce function. here tried doesnt work:

 var ca =   uniquearray.reduce(function(pval, elem) {     var spl = elem.split(',');             var difference = math.round(spl[1] - spl[0]);             return difference;     },elem.split(',')[3]); 

i dont think can done in 1 pass, wrong. i'd go 2 step...

1. reduce array unique map of px values
2. map result array in required format

var input = ["0,5,p1", "24,29,p2", "78,83,p2", "78,83,p3", "162,167,p2" ]     var step1 = input.reduce(function(p,c){      var parts = c.split(",");      if(!p[parts[2]])         p[parts[2]] = 0;      p[parts[2]] += parseint(parts[1],10) - parseint(parts[0],10);      return p;  },{});    var result = object.keys(step1).map(function(e){      return step1[e] + "," + e;  });    console.log(result);