var naviPlace="home";

function naviAction(button){
    buttonArray = document.getElementById("navi").getElementsByTagName("img");
    for (i in buttonArray){
        if (buttonArray[i].id == button){
        str = buttonArray[i].src;
        newSrcValue = str.replace(/up/,"dwn");
        document.getElementById(button).src = newSrcValue;
        getContent(button);
        } else {
            if (buttonArray[i].id){
                str = buttonArray[i].src;
                newSrcValue = str.replace(/dwn/,"up");
                document.getElementById(buttonArray[i].id).src = newSrcValue;
            }
        }
    }
}

function getContent(value){
    naviPlace = value;
    naviHover(value,'out');
    switch (value){
    case "home":
        document.getElementById('top').className = "homeNavi";
        document.getElementById('mainContent').className = "mainContent";
    break;
    default:
    document.getElementById('top').className = "otherNavi";
    document.getElementById('mainContent').className = "mainContent2";
    break;
    }
    document.getElementById('mainContent').innerHTML = contentArray[value];
}

function naviHover(id,value){
    switch (value){
        case "out":
            buttonSource = document.getElementById(id).src;
            if (id != naviPlace){
               document.getElementById(id).src = buttonSource.replace(/dwn/,"up");
            }
        break;
        case "over":
            buttonSource = document.getElementById(id).src;
                document.getElementById(id).src = buttonSource.replace(/up/,"dwn");
        break;
        default:
        break;
    }
}