Problème avec la fonction confirm()

<SCRIPT LANGUAGE="Javascript">

window.onerror=new Function("return true")

var dx;

var dy;

var scor = 0;

var dod;

var pscor = 0;

var escor = 0;

var point;

var los;

var reversal = 0;





function startUp()

{

score.scorebox.value = " "

score.box.value= " "

score.reverse.value = " "

}



function initialize()

{

dx = 2;

dy = 2;

los = Math.round(21 * Math.random()) + 1;

point = 0;

hefr = Math.round(200 * Math.random()) + 35;

vred = Math.round(100 * Math.random()) + 100;

ball.style.posTop = hefr;

ball.style.posLeft = vred;



moveBall()

}



function moveBall()

{



var xp = ball.style.posLeft;

var yp = ball.style.posTop;

var sig = paddle.style.posTop;

var gis = paddle.style.posLeft;

var hit = document.elementFromPoint(xp,yp);

var pore = 215

var place = pore - 1; 



if (point < 7)

{

if ((yp >= 15) && (yp <= 215))

paddle.style.posTop = yp - 6;

else

paddle.style.posTop = place

}

if (point >= 7)

{

if ((yp >= 15) && (yp <= 215))

paddle.style.posTop = yp + 13;

else

paddle.style.posTop = place

}



if ((yp < 27) || (yp > 258))

dy = dy * -1



if (point >= 15)

paddle.style.posTop = sig



if (xp >= 358){

escor = escor + .5

score.scorebox.value = " " +escor+ " "

gameLose()

return

}



if (xp <= 27)

{

pscor = pscor + .5

score.box.value = " " +pscor+ " "

gameWin()

return

}





if (hit != null)

{

if (hit.id == "paddle"){

dx = dx * -1;

point = point + 1

}

else if (hit.id == "enemy") {

dx = dx * -1;

}

}







ball.style.posTop += dy

ball.style.posLeft += dx







window.setTimeout("moveBall()", 1, "JavaScript");





}



function movePaddle()

{

var ypos = window.event.y;

if ((ypos >= 15) && (ypos <= 230))

enemy.style.posTop = ypos;

}



function gameLose()

{

if (escor >= 15){

goal.style.visibility = "hidden"

lose.style.visibility = "visible"

alert("L'ordinateur vous a battu " +escor+ " à " +pscor+ ".")

history.go(0)

}

else

return

}



function gameWin()

{

if (pscor >= 15){

goal.style.visibility = "hidden"

win.style.visibility = "visible"

alert("Vous avez battu l'ordinateur " +pscor+ " à " +escor+ " !!!")

history.go(0)

}

else

return

}



function reverseIt()

{

if (reversal <= 9)

{

if (window.event.keyCode == 118){

dy = dy * -1

reversal = reversal + 1

score.reverse.value = reversal

}

if (window.event.keyCode == 104){

dx = dx * -1

reversal = reversal + 1

score.reverse.value = reversal

}

}

}
</SCRIPT>