怎么设定滚动条一次滚动的大小

Question

<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<p>ballack
<script>
document.onclick=myscroll;
function myscroll()
{
document.body.scrollTop++;
}
</script>

Answer 1

效果比较怪啊
<p>ballack1
<p>ballack2
<p>ballack3
<p>ballack4
<p>ballack5
<p>ballack6
<p>ballack7
<p>ballack8
<p>ballack9
<p>ballack0
<p>ballack1
<p>ballack2
<p>ballack3
<p>ballack4
<p>ballack5
<p>ballack6
<p>ballack7
<p>ballack8
<p>ballack9
<p>ballack0
<script>
lasttop=0;
function myscroll()
{
if(document.body.scrollTop>lasttop)
{
document.body.scrollTop=lasttop+1;
}
else
if(document.body.scrollTop<lasttop)
{
document.body.scrollTop=lasttop-1;
}
lasttop=document.body.scrollTop;
setTimeout(myscroll,100);
}
myscroll();
</script>