Scroll left and right wont work if the page is not wider than the screen. You have assigned scrollLeft to the key 40 (down) so nothing will happen. The following code is corrected and works for up and down:
var handler = function(e) {
e = e || window.event;
var k = e.keyCode || e.which;
switch(k) {
case 37:
console.log("37 pressed");
document.body.scrollLeft -= 1000;
document.documentElement.scrollLeft -= 1000;
break;
case 38:
console.log("38 pressed");
document.body.scrollTop-= 1000;
document.documentElement.scrollTop-= 1000;
break;
case 39:
console.log("39 pressed");
document.body.scrollLeft += 1000;
document.documentElement.scrollLeft += 1000;
break;
case 40:
console.log("40 pressed");
document.body.scrollTop += 1000;
document.documentElement.scrollTop += 1000;
break;
default: return true;
}
if( e.preventDefault) e.preventDefault();
return false;
};
if( window.attachEvent) window.addEvent("onkeydown",handler,false);
else window.addEventListener("keydown",handler,false);