function changeImage(btn)
{
    if(btn.parentNode.className=='photo-left')
    {
        imgIndex = imgIndex - 1;
        document.getElementById('photo').src = imgArray[imgIndex][0];
        document.getElementById('photoName').innerHTML = imgArray[imgIndex][1]
    }
    else
    {
        imgIndex = imgIndex + 1
        document.getElementById('photo').src = imgArray[imgIndex][0];
        document.getElementById('photoName').innerHTML = imgArray[imgIndex][1]
    }
    
    photoNavigation();
}

function imgInit()
{
    if(document.getElementById('photo'))
    {
        document.getElementById('photo').src = imgArray[imgIndex][0];
        document.getElementById('photoName').innerHTML = imgArray[imgIndex][1]
        photoNavigation();
    }
    
    
}

function photoNavigation()
{
    if(imgIndex == 1)
    {
        document.getElementById('left').style.visibility='hidden';
    }
    else
    {
        document.getElementById('left').style.visibility='visible';
    }
    
    if(imgIndex == imgArray.length - 1)
    {
        document.getElementById('right').style.visibility='hidden';
    }
    else
    {
        document.getElementById('right').style.visibility='visible';
    }
}