DHTML:预加载图片轮显

最新推荐文章于 2025-07-11 10:13:21 发布

转载最新推荐文章于 2025-07-11 10:13:21 发布 · 413 阅读

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#download #function #button #image #string #object

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本文介绍了一个使用JavaScript实现的简单幻灯片展示脚本，该脚本通过预加载图片来提升幻灯片切换速度，并提供了前后切换按钮。此脚本适用于网页中需要展示多张图片的场景。

<html><head>
<script language="JavaScript">

//Preloaded slideshow script- By Jason Moon
//For this script and more
//Visit <a href="http://www.dynamicdrive.com " target="_blank">http://www.dynamicdrive.com </a>

// PUT THE URL'S OF YOUR IMAGES INTO THIS ARRAY...
var Slides = new Array('attachments/month_054/poster_50first_dates.jpg','attachments/month_054/poster_snickets.jpg','attachments/month_054/poster_she_s_french.jpg');

// DO NOT EDIT BELOW THIS LINE!
function CacheImage(ImageSource) { // TURNS THE STRING INTO AN IMAGE OBJECT
   var ImageObject = new Image();
   ImageObject.src = ImageSource;
   return ImageObject;
}

function ShowSlide(Direction) {
   if (SlideReady) {
      NextSlide = CurrentSlide + Direction;
      // THIS WILL DISABLE THE BUTTONS (IE-ONLY)
      document.SlideShow.Previous.disabled = (NextSlide == 0);
      document.SlideShow.Next.disabled = (NextSlide ==
(Slides.length-1));
if ((NextSlide >= 0) && (NextSlide < Slides.length)) {
            document.images['Screen'].src = Slides[NextSlide].src;
            CurrentSlide = NextSlide++;
            Message = 'Picture ' + (CurrentSlide+1) + ' of ' +
Slides.length;
            self.defaultStatus = Message;
            if (Direction == 1) CacheNextSlide();
      }
      return true;
   }
}

function Download() {
   if (Slides[NextSlide].complete) {
      SlideReady = true;
      self.defaultStatus = Message;
   }
   else setTimeout("Download()", 100); // CHECKS DOWNLOAD STATUS EVERY 100 MS
   return true;
}

function CacheNextSlide() {
   if ((NextSlide < Slides.length) && (typeof Slides[NextSlide] ==
'string'))
{ // ONLY CACHES THE IMAGES ONCE
      SlideReady = false;
      self.defaultStatus = 'Downloading next picture...';
      Slides[NextSlide] = CacheImage(Slides[NextSlide]);
      Download();
   }
   return true;
}

function StartSlideShow() {
   CurrentSlide = -1;
   Slides[0] = CacheImage(Slides[0]);
   SlideReady = true;
   ShowSlide(1);
}
</script>
<head>
<body onLoad="StartSlideShow()">
<form name="SlideShow">
<table>
<tr>
   <td colspan=2><img name="Screen" width=200 height=300></td>
</tr>
<tr>
   <td><input type="button" name="Previous"
value=" << "
onClick="ShowSlide(-1)"></td>
   <td align="right"><input type="button" name="Next"
value=" >> " onClick="ShowSlide(1)"></td>
</table>
</form>
</body></html>