Slide 22

document.addEventListener("keydown",keyHit,false);
var thisPic = 0;
function keyHit(evt) {
var myPix = new Array("images/catseyenebula.jpg", "images/crabnebula.jpg","images/eskimonebula.jpg", "images/ringnebula.jpg");
var imgCt = myPix.length-1;
var ltArrow = 37;
var rtArrow = 39;
if (evt) {
var thisKey = evt.which;
}
else {
var thisKey = window.event.keyCode;
}
if (thisKey == ltArrow) {
chgSlide(-1);
}
else if (thisKey == rtArrow) {
chgSlide(1);
}
function chgSlide(direction) {
thisPic = thisPic + direction;
if (thisPic > imgCt) {
thisPic = 0;
}
if (thisPic < 0) {
thisPic = imgCt;
}
document.getElementById("myPicture").src = myPix[thisPic];
}
}