Javascript Data Structure Interval

function Interval(a, b) {
  this.start = a;//w  w w . j  av  a 2s  .  c  o m
  this.end = b;
}

function merge(intervals) {
  if (intervals.length < 2) {
    return intervals;
  }
  //sorted before comparing to merge
  intervals.sort(function(a, b) {
    if (a.start < b.start) {
      return -1;
    }
    else if (a.start > b.start) {
      return 1;
    }
    else {
      return 0;
    }
  });

  var result = [];

  var previous = intervals[0];
  for (var i = 1; i < intervals.length; i++) {
    var current = intervals[i];
    if (previous.end >= current.start) {
      var mergeInterval = new Interval(previous.start, Math.max(previous.end, current.end));
      previous = mergeInterval;
    }
    else {
      result.push(previous);
      previous = current;
    }
  }
  result.push(previous);

  return result;
}

var test = [new Interval(1, 3),new Interval(8, 10), new Interval(15, 18), new Interval(2, 6)];

console.log(merge(test));