function changeImage() {
    for (var i = 0; i < changeImage.arguments.length; i += 2)
        document.images[changeImage.arguments[i]].src = changeImage.arguments[i + 1];
}

function changeBackgroundImage() {
    for (var i = 0; i < changeBackgroundImage.arguments.length; i += 2) {
        findElementById(changeBackgroundImage.arguments[i]).style.backgroundImage = "url(" + changeBackgroundImage.arguments[i + 1] + ")";
    }
}

function switchBackgroundImage() {
    for (var i = 0; i < switchBackgroundImage.arguments.length; i += 3) {
        var element = findElementById(switchBackgroundImage.arguments[i]);
        if (element.style.backgroundImage == "url(" + switchBackgroundImage.arguments[i + 2] + ")") element.style.backgroundImage = "url(" + switchBackgroundImage.arguments[i + 1] + ")";
        else element.style.backgroundImage = "url(" + switchBackgroundImage.arguments[i + 2] + ")";
    }
}

function preloadImage() {
    for (var i = 0; i < preloadImage.arguments.length; i++) {
        document.images[document.images.length] = newImage(preloadImage.arguments[i]);
    }
}

function newImage(arg) {
    rslt = new Image();
    rslt.src = arg;
    return rslt;
}