curr = 0;

function imageNext(id,move) {
 if (move == 1 ) {
    curr++;
    if (curr == images.length) {
       curr = 0;
       }
    }
 else {
    curr -= 1;
    if (curr < 0) {
       curr = images.length -1;
       }
    }
 document.getElementById(id).src = images[curr];
 }