crypto_js_solution.js

Array.prototype.each_slice = function (size, callback){
    console.log(this.length, 'Size', size, 'Callback', callback);
    for (var i = 0, l = this.length; i < l; i += size){
        callback.call(this, this.slice(i, i + size));
    }
};

var Crypto = function(messageString){
    this.message = messageString;
}

Crypto.prototype.normalizePlainText = function(){
     plainText = _.map(this.message, function(character){
            return character.toLowerCase();
        })
        
     var results = _.filter(plainText, function(character){
            return character.search(/[a-z]+/) == 0;
        })
     return results;
}
//Adding methods;
Crypto.prototype.plainTextSegments = function(){
    var length = Math.ceil(Math.sqrt(this.normalizePlainText().length));
    var segments = []
    this.normalizePlainText().each_slice(length, function(segment){
        segments.push(segment);
    })
    return segments;
}

Crypto.prototype.cipherText = function(){
    cipherArray = []
    _.each(this.plainTextSegments(), function(segment){
        _.each(segment, function(letter, index){
            cipherArray[index] = cipherArray[index] || [];
            cipherArray.push(letter);
        })
    })

    return cipherArray.join('');
}
//Instantiated a new Crypto object
var crypto1 = new Crypto('This is a secret message');