scrolling using buttons designed with javascript

<div style="background-color="orange";width:155"><center>
<a href="java script:movedown();"	onMouseDown="java script:movedown();" 	onMouseUp="java script:stopscroll();"><img src="down1.bmp" /></a>
<a href="java script:moveup();" 		onMouseDown="java script:moveup();" 		onMouseUp="stopscroll();"><img src="top1.bmp" /></a>
<a href="java script:moveright();"	onMouseDown="java script:moveright();" 	onMouseUp="stopscroll();"><img src="right1.bmp" /></a>
<a href="java script:moveleft();" 	onMouseDown="java script:moveleft();"	onMouseUp="stopscroll();"><img src="left1.bmp" /></a>
<a href="java script:stopscroll();" 	onMouseDown="java script:stopscroll();"><img src="stop1.bmp" ></a><br />
<a href="java script:movetop();"><b>Top of the table</b></a>
<a href="java script:moveside();"><b>side of the table</b></a><br /></center>
</div>

function movedown(){
if (window.moveupvar) clearTimeout(moveupvar)
if (iens6&&parseInt(crossobj.style.top)>=(contentheight*(-1)+155))
crossobj.style.top=parseInt(crossobj.style.top)-speed
else if (ns4&&crossobj.top>=(contentheight*(-1)+100))
crossobj.top-=speed
movedownvar=setTimeout("movedown()",100)
}

function moveup(){
if (window.movedownvar) clearTimeout(movedownvar)
if (iens6&&parseInt(crossobj.style.top)<=0)
crossobj.style.top=parseInt(crossobj.style.top)+speed
else if (ns4&&crossobj.top<=0)
crossobj.top+=speed
moveupvar=setTimeout("moveup()",100)
}

function moveright(){
if (window.moveleftvar) clearTimeout(moveleftvar)
if (iens6&&parseInt(crossobj.style.left)>=(contentwidth*(-1)+100))
crossobj.style.left=parseInt(crossobj.style.left)-speed
else if (ns4&&crossobj.top>=(contentwidth*(-1)+200))
crossobj.left-=speed
moverightvar=setTimeout("moveright()",100)
}

function moveleft(){
if (window.moverightvar) clearTimeout(moverightvar)
if (iens6&&parseInt(crossobj.style.left)<=0)
crossobj.style.left=parseInt(crossobj.style.left)+speed
else if (ns4&&crossobj.left<=0)
crossobj.left+=speed
moveleftvar=setTimeout("moveleft()",100)
}

function stopscroll(){
if (window.moveupvar) clearTimeout(moveupvar)
if (window.movedownvar) clearTimeout(movedownvar)
if (window.moverightvar) clearTimeout(moverightvar)
if (window.moveleftvar) clearTimeout(moveleftvar)
}