Did you enjoy the pure JavaScript poker hand analyzer to be used (also) in puzzle games I posted earlier this week? Unfortunately there was a glitch causing the function to detect Ace Straight not to work properly. I fixed it, and to give you some extra value I commented the source code so you can learn how it’s done. This is the fixed result of the script: And this is the commented source code:

<html&gt;
<head&gt;
<meta charset="UTF-8"&gt;
</head&gt;
<body&gt;
<div id = "table"&gt;</div&gt;
<div id = "result" style = "font:normal 32px arial;margin:10px;"&gt;</div&gt;

<script&gt;

// this is the array with your actual hand. It will contain five numbers - the five cards - ranging from zero (the first Ace) to 51 (the last King)
var hand = [];

// this is a temporary array which will contain the modulo operation of each "hand" array element by 13. This will cause this array to be only filled by
// numbers from 0 (Ace) to 12 (King) no matter the suit
var valuesArray = [];

// this is a temporary array which will contain the suits of your original hand
var suitsArray = [];

// convertHand function will populate valuesArray and suitsArray starting from hand array
function convertHand(){
     for(var i = 0; i < 5; i ++){
          valuesArray[i] = hand[i] % 13;
          suitsArray[i] = Math.floor(hand[i] / 13);     
     }
}

// given a value "n", returns the number of occurrences of "n" in "hand" array. Useful to know how many "two"s or "three"s and so on we have on a hand
function occurrencesOf(n){
     var count = 0;
     var index = 0;   
     do{          
          index = valuesArray.indexOf(n, index) + 1;  
          if(index == 0){
               break;
          }
          else{
               count ++;
          }
     } while(index < valuesArray.length);
     return count;
}

// thanks to occurrencesOf, this function returns a string with the combination of duplicate cards.
// If you have "Four of a Kind" it will return "4", if you have "Three of a kind" il will return "3",
// if you have "Full House" it will return "32" or "23" and so on.
function duplicateCards(){
     var occurrencesFound = []; 
     var result = "";
     for(var i = 0; i < valuesArray.length; i++){
          var occurrences = occurrencesOf(valuesArray[i]);
          if(occurrences &gt; 1 &amp;&amp; occurrencesFound.indexOf(valuesArray[i]) == -1){
               result += occurrences; 
               occurrencesFound.push(valuesArray[i]);    
          }
     }
     return result;
}

// this function will return the lowest number in a hand. Useful to check for straights
function getLowest(){
     var min = 12;
     for(var i = 0; i < valuesArray.length; i++){
          min = Math.min(min, valuesArray[i]);     
     }
     return min;     
}

// we have a straight when starting from the lowest card we can find an occurrence of lowest card +1, +2, +3 and +4
function isStraight(){
     var lowest = getLowest();
     for(var i = 1; i < 5; i++){ 
          if(occurrencesOf(lowest + i) != 1){
               return false
          }     
     }
     return true;
}

// we have an ace straight when you have 10 (9), J (10), Q (11), K (12) and A (0)
function isAceStraight(){
     var lowest = 8;
     for(var i = 1; i < 5; i++){
          if(occurrencesOf(lowest + i) != 1){
               return false;
          }     
     }
     return occurrencesOf(0) == 1;
}

// we have a flush when all items in suitsArray have the same value
function isFlush(){
     for(var i = 0; i < 4; i ++){
          if(suitsArray[i] != suitsArray[i+1]){
               return false;
          }
     }
     return true;
}  

// main function to check the hand
function checkHand(){
     // just a string to output the result
     var resultString = "";
     // populating hand array with the values of the five <select&gt; elements
     for(var i = 0; i < 5; i++){
          hand[i] = document.getElementById("card_" + i).value;
     }
     // calling convertHand to create valuesArray and suitsArray
     convertHand();
     switch(duplicateCards()){
          case "2":
               resultString = "1 Pair";
               break;
           case "22":
               resultString = "2 Pairs";
               break;
          case "3":
               resultString = "3 of a Kind";
               break;
          case "23":
          case "32":
               resultString = "Full House";
               break;
          case "4":
               resultString = "4 of a Kind";
               break;
          case "5":
               resultString = "5 of a Kind";
               break;
          default:
               if(isStraight()){
                    resultString = "Straight";     
               }
               if(isAceStraight()){
                    resultString = "Ace Straight";
               }
               break;
     }
     if(isFlush()){
          if(resultString){
               resultString += " and Flush";     
          }
          else{
               resultString = "Flush";
          }
     }
     if(!resultString){
          resultString = "nothing...";
     }
     document.getElementById("result").innerHTML = resultString;
}  

// THE REMAINING CODE IS USED JUST TO DRAW THE "CARDS" ON THE SCREEN AND TRIGGER WHEN THE PLAYER CHANGES A "CARD"

var cardSymbols = ["A", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K"];
var suitSymbols = ["?", "?", "?", "?"];
var tableHTML = '';
for(var j = 0; j < 5; j ++){
     tableHTML += '<select style = "padding:3px;font:normal 32px arial;margin:10px" id = "card_' + j + '" onchange = "checkHand();"&gt;';
     for(var i = 0; i < 52; i ++){
          tableHTML += '<option value = "' + i + '"&gt;' + cardSymbols[i % 13] + " " + suitSymbols[Math.floor(i / 13)] + '</option&gt;';  
     }
     tableHTML += '</select&gt;';   
}
document.getElementById("table").innerHTML = tableHTML;
checkHand();
     
</script&gt;

</body&gt;
</html&gt;

You can download the source code, and next week I’ll show you an example of this engine in action.