ตัวแปรใน javascript จะนำออกมาใช้ยังไงครับ ใน tag HTML อย่างไร

<script type="text/javascript">
<!--
function BwindowWidth()
{
 if (window.innerWidth) return window.innerWidth;
 else if (document.body && document.body.offsetWidth) return document.body.offsetWidth;
 else return 0;
}

function BwindowHeight()
{
 if (window.innerHeight) return window.innerHeight;
 else if (document.body && document.body.offsetHeight) return document.body.offsetHeight;
 else return 0;
}

function recal()
{
 if (Width != BwindowWidth() || Height != BwindowHeight())
 window.history.go(0);
}

/*initialization for NetScape */
if(!window.Width && window.innerWidth)
  {
   window.onresize = recal;
   Width = BwindowWidth();
   Height = BwindowHeight();
  }

//-->
</script>


<script type="text/JavaScript">
<!--
/*initialization for Internet Explorer !!! Leave this funtion between the body tag */
 if(!window.Width && document.body && document.body.offsetWidth)
  {
   window.onresize = recal;
   Width = BwindowWidth();
   Height = BwindowHeight();
 }
//-->
</script>

<script type="text/javascript">
<!--
 document.write("หน้านี้มีขนาด "+Width +"  X "+Height);


//-->
</script>

<img src="img/chart.png" width=" Width   ">