var MyString = function(source){

  var arr = [];

  for(var index in source){

    arr.push(source[index]);

    //Public property

    this[index] = source[index];

  }

  //Public property

  this['length'] = arr.length;

  //Public getter

  this.getStringArray = function() {

    return arr;

  }

};

​

MyString.prototype.toString = function(){

  return this.getStringArray().join('');

};

​

​

MyString.prototype.charAt = function(i){

  return this.getStringArray()[i];

};

​

​

MyString.prototype.concat = function(source2){

  return this.toString() + source2;

};

​

MyString.prototype.slice = function(start, end){

  var slice = '';

  var arr = this.getStringArray();

  for(var i=start; i < end; i++){

    slice += arr[i];

  }

  return slice;

};

​

MyString.prototype.split = function(char){

  var pre = '', post = '', split = '';

  var arr = this.getStringArray();

  var i = 0;

  while(arr[i] != char){

    pre += arr[i++];

  }

  i++;

  while(arr[i] !== undefined){

    post += arr[i++];

  }

  return [pre, split, post];

};

​

MyString.prototype.reverse = function(){

  var arr = this.getStringArray();

  var s = '';

  for(var i = arr.length - 1; i >= 0; i--){

    s += arr[i];

  }

  return s;

}

​

​

​