JavaScript学习摘记(实现标题左右滚动效果)

<title>走马灯测试</title>
<script type="text/javascript">
var dir = "left";
function scroll() {
var title = document.title;
if (dir == "left") {
var firstch = title.charAt(0);
var leftstr = title.substring(1, title.length);
document.title = leftstr + firstch;
}
else if (dir == "right") {
var lastch = title.charAt(title.length - 1);
var leftstr = title.substring(0, title.length - 1);
document.title = lastch + leftstr;
}
else {
alert("错误的方向值！");
}
}

function setDir(d) {
dir = d;
}
setInterval("scroll()", 500);
</script>