String shuffle and random and

string-shuffle.js

// 文字列シャッフル
String.prototype.shuffle = function() {
  var result = [];
  var ary = this.split("");
  var l = ary.length;
  for (var i = 0;i < l;i++) {
    var random = Math.floor(Math.random()*ary.length);
    result.push(ary[random]);
    ary.splice(random,1);
  }
  return result.join("");
};

// 文字列をcount数分ランダムで返す
String.prototype.random = function(count) {
  var result = [];
  var ary = this.split("");
  var l = count || ary.length;
  for (var i = 0;i < l;i++) {
    var random = Math.floor(Math.random()*ary.length);
    result.push(ary[random]);
  }
  return result.join("");
};

// 文字列中に含まれる各文字の数をカウントする
String.prototype.charCount =function() {
  var l = this.length;
  var result = {};
  for (var i = 0;i<l ;i++) {
    if (result[this[i]] == undefined) {
      result[this[i]] = 0;
    }
      result[this[i]] = result[this[i]] + 1;
  }
  return result;
};