window.onload = loadImg;

document.onkeydown = keyHit;

myImgSrc = "images/";
myImgEnd = ".jpg"
var i = 0;
var max = 0;

function loadImg(){
    i = 0;
    max = this.myCap.length - 1;
    document.getElementById('caption').innerHTML = myCap[i];
    document.imgSrc.src = myImgSrc + myImg[i] + myImgEnd;
}

function pick(tmb){
    i = tmb;
    document.getElementById('caption').innerHTML = myCap[i];
    document.imgSrc.src = myImgSrc + myImg[i] + myImgEnd;
}

function prev(){
    if(i>0){
        i--;
    } 
    document.getElementById('caption').innerHTML = myCap[i];
    document.imgSrc.src = myImgSrc + myImg[i] + myImgEnd;
}

function next(){
    if(i<max){
        i++;
    } 
    document.getElementById('caption').innerHTML = myCap[i];
    document.imgSrc.src = myImgSrc + myImg[i] + myImgEnd;
}

function keyHit(evt){
    var ltArrow = 37;
    var rtArrow = 39;
    var thisKey = (evt) ? evt.which : window.event.keyCode;
    if (thisKey == ltArrow) {
        prev();
    }
    else if (thisKey == rtArrow){
        next()
    }
    return false;
}