Permutation class

Permutation.js

var Permutation = function(str){
  this.construct(str);
};

Permutation.prototype.originalString = undefined;
Permutation.prototype.results        = new Object();
Permutation.prototype.mirrorResults  = new Object();
Permutation.prototype.usedChars      = new Array();

Permutation.prototype.construct = function(str){
  this.originalString = str.toLowerCase();
};

Permutation.prototype.getPermutation = function(){
  this._permutate(this.originalString);
  this.results = Object.keys(this.results);
  return this.results;
};

Permutation.prototype.getMirrors = function(){
  this._findMirrors();
  this.mirrorResults = Object.keys(this.mirrorResults);
  return this.mirrorResults;
};

Permutation.prototype._permutate = function (str) {
  var currentChar, allChars = str.split("");
  for (var i = 0; i < allChars.length; i++) {
    currentChar = allChars.splice(i, 1);
    this.usedChars.push(currentChar);
    if (allChars.length == 0) {
      this.results[this.usedChars.join("")] = undefined;
    }
    this._permutate(allChars.join(""));
    allChars.splice(i, 0, currentChar);
    this.usedChars.pop();
  }
};

Permutation.prototype._findMirrors = function(){
  var stringLength = this.originalString.length,
      halfLength   = stringLength / 2;
  
  if (stringLength % 2 === 1) {
    return false;
  }
  
  if (!this.results) {
    this.getPermutation();
  }
  
  this.results.forEach(function(value){
    var firstHalf = '',
        secondHalf = '';
    
    for (var i = 0; i < halfLength; i ++) {
      firstHalf  += value[i];
      secondHalf += value[((halfLength * 2 - 1) - i)];
    }
    
    if (firstHalf === secondHalf) {
      this.mirrorResults[value] = undefined;
    }
  }.bind(this))
};

var Permutator = new Permutation('telet');

console.log('Permutations', Permutator.getPermutation());
console.log('Mirrors', Permutator.getMirrors());