Question

This is my code. It alert()’s NaN everytime.

function updateScore(action){
    var cookieArray = document.cookie.split(";");
    var encodedURL = cookieArray[2];
    var decodedURL = decodeURIComponent(encodedURL); 
    //check if cookie exists
    if (decodedURL == "undefined"){ 
        setCookie("rrcookie_score","0",1)
    }
    var oldScore = decodedURL.split('=');
    //alert(oldScore[1]);
    var oldScoreInt = parseInt(oldScore);
    var newScore = oldScoreInt + 1;
    alert(newScore);
} 

Answer 1

Have you tried

var oldScoreInt = parseInt(oldScore[1]);

For sure parseInt(oldScore) wont work since oldScore is an array.
Furthermore what happens if multiple parameters in the URL, the whole code needs some rethinking.

T.