var quickSort = (function(){
    var items;

    var less = function(a, b) { return compare(items[a], items[b]) < 0; };

    var sort = function(items, lo, high) {
      if(high <= lo) { return; }
      mid = partition(items, high, lo);
      sort(items, lo, mid-1);
      sort(items, mid+1, high);
    };

    var exch = function(a, i, j) {
      var x = a[i];
      a[i] = a[j];
      a[j] = x;
    };

    var compare = function(valA, valB) {
      if(valA > valB)   { return 1;  }
      if(valA === valB) { return 0;  }
      if(valA < valB)   { return -1; }
    };

    var partition = function(items, high, lo)  {
      var i = lo;
      var j = high + 1;

      while(true) {
        while(less(++i, lo)) { if(i === high) { break; } }
        while(less(lo, --j)) { if(j === lo) { break; } }
        if(i >= j) { break; }
        exch(items, i, j);
      }
      exch(items, lo, j);
      return j;
    };

    var shuffle = function(arr) {
      var len = arr.length;
      for(var i = len - 1; i > 0; i--) {
        var j = Math.round(Math.random() * i);
        var hole = arr[i];
        arr[i] = arr[j];
        arr[j] = hole;
      }
      return arr;
    };

    return {
      sort: function(arr) {
        items = shuffle(arr);
        sort(items, 0, items.length-1);
      }
    };
})();

var arr = ['j','a','k','b','e','h','f','d','i','c','g'];
quickSort.sort(arr);
console.log(arr);