📄 ch11_q2.htm

📁 javascript source code part1

💻 HTM

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<HTML>
<HEAD>
<SCRIPT LANGUAGE=JavaScript>

function getCookieValue(cookieName)
{
   var cookieValue = document.cookie;
   var cookieStartsAt = cookieValue.indexOf(" " + cookieName + "=");

  if (cookieStartsAt == -1)
  {
      cookieStartsAt = cookieValue.indexOf(cookieName + "=");
  }

   if (cookieStartsAt == -1)
   {
      cookieValue = null;
   }
   else
   {

      cookieStartsAt = cookieValue.indexOf("=", cookieStartsAt) + 1;
      var cookieEndsAt = cookieValue.indexOf(";", cookieStartsAt);
      if (cookieEndsAt == -1)
         cookieEndsAt = cookieValue.length;
      cookieValue = unescape(cookieValue.substring(cookieStartsAt, cookieEndsAt));

   }

   return cookieValue;
}

function setCookie(cookieName,cookieValue, cookiePath, cookieExpires)
{
   cookieValue = escape(cookieValue);
   if (cookieExpires == "")
   {
      var nowDate = new Date();
      nowDate.setMonth(nowDate.getMonth() + 6);
      cookieExpires = nowDate.toGMTString();
   }

   if (cookiePath != "")
   {
      cookiePath = ";Path=" + cookiePath;
   }
   document.cookie = cookieName + "=" + cookieValue + ";Expires=" + cookieExpires + cookiePath;
}

</SCRIPT>
</HEAD>
<BODY>
<IMG SRC="AdvertImage1.jpg" NAME="imgAdvert">
<SCRIPT>

var imageNumber = getCookieValue("displayedImages");
var totalImages = 3;

if (imageNumber == null)
{
   imageNumber = "1";
}
else
{
   imageNumber = Math.floor(imageNumber) + 1;
}

if (totalImages == imageNumber)
{
   setCookie("displayedImages","","","Mon, 1 Jan 1970 00:00:00")
}
else
{
   setCookie("displayedImages",imageNumber,"","")
}

document.imgAdvert.src = "AdvertImage" + imageNumber + ".jpg";
</SCRIPT>
</BODY>
</HTML>

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