Hangman learning AI

I have been learning AngularJS and have written my first app. It's a Hangman AI which learns words and guesses the solution based on the words it knows.

Please look over my code and provide some pointers towards better practices, techniques and overall criticism.

Here is a CodePen demo, as the Stack Snippet may have cross-site AJAX issues.



`var app = angular.module("HangManAI", []);

app.controller('HangManController', ['$scope', '$http', function($scope, $http){
$scope.step = 0;
$scope.theWords = new Array();
$scope.wordCount = 0;
$scope.wordLetters = new Array();
$scope.myGuess = "None";
$scope.testString = "";
$scope.attempts =10;
$scope.letterFound = false;
$scope.myMouth = "G'Day. I am a hangman AI written with AngularJS. I can win a game of hangman against you if I know the words you use. Click New Game to begin.";
$scope.error = "";

var availableLetters = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"];
var knownWords = [];

//Functions
$scope.startAGame = function(){
$scope.theWords = new Array();
$scope.wordCount = 0;
$scope.attempts = 10;
$scope.error = "";
availableLetters = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"];
$scope.myMouth = "Alright! First tell me how many words there are and how many letters for each word.";
$scope.step = 1;
var req = {
method: 'GET',
url: 'http://www.hott-source.com/hangman/getMemory.php',
data: { }
}
$http(req).then(function(response){
knownWords = response.data;
$scope.testString = knownWords;

}, function(response){
$scope.error = "I could not get my memory. Try reloading the page.";
});
}
$scope.checkWords = function(){
//Loop through each typed word
var i = $scope.theWords.length;
var wordKnown = false;
var newWords = "";
var whatToSay = "";

Here are a few general feedbacks:

Have a coherent code style

You're mixing multiple code styles

• sometimes you put spaces around operators ng-show='step == 0', sometimes you don't ng-show='step==2'

-
sometimes you put braces on same line $scope.checkWords = function(){, sometimes you don't

$scope.nextLetter = function()
{

Coherent code style improves readability, some IDEs have reformatting tools to help with this issue.

Avoid extending Javascript's classes

Prefer a function

function deleteElem(array, val) {
    var index = array.indexOf(val);
    if (index >= 0) array.splice(index, 1);
    return array;
}

over extending Array.prototype

Array.prototype.deleteElem = function(val) { /*...*/ }

Who knows what will happen in future releases of Javascript? That may break your code, or you may break another library's code.

Avoid writing initialization values at multiple places

["A", "B", "C", "D", "E", "F", "G", "H" ... is a big initialization value. If it contains an error, you don't want to have to fix it at multiple places.
You can extract the value in a constant, and clone it to initialize the variable.

var ALL_AVAILABLE_LETTERS = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"];
var availableLetters = ALL_AVAILABLE_LETTERS.concat(); //clone the array

Learn about character code and character comparison

That will probably help you simplify your algorithms. For example, you can rewrite fixLetter like this:

$scope.fixLetter = function(letterIndex, wordIndex) {
    var aWord = this.theWords[wordIndex].word;
    var aLetter = aWord[letterIndex];
    if(aLetter >= 'A' && aLetter < 'Z') {
        aLetter = String.fromCharCode(aLetter.charCodeAt(0) + 1);
    } else if(aLetter === 'Z') {
        aLetter = 'A';
    } else { //default
        aLetter = 'A';
    }
    aWord = aWord.replaceAt(letterIndex, aLetter);
    this.theWords[wordIndex].word = aWord;
}

Some documentation can be found on MDN: charCodeAt, fromCharCode

Comment intended empty blocks

It seems like you have a bug or unfinished stuff there:

if(typeof knownWords[currentWord.length-1] === 'undefined')
{

}

If you intend it to be empty, you can inverse the condition to avoid the else:

if(!(typeof knownWords[currentWord.length-1] === 'undefined'))
{
    var innerLoop = ...
}

Or you can add a comment:

if(typeof knownWords[currentWord.length-1] === 'undefined')
{
    //Do nothing (on purpose)
}

If it's unfinished code, add a TODO

if(typeof knownWords[currentWord.length-1] === 'undefined')
{
    //TODO [Describe what you need to code here]
}

StackExchange Code Review Q#121742, answer score: 7