js图片缓冲加载代码实例

<script type="text/javascript"> 
var Imgvalue; 
var Count =13;//图片数量 
var Imgs = new Array(Count); 
var ImgLoaded =0; 
//预加载图片 
function preLoadImgs() 
{ 
  alert(‘图片加载中请稍等......‘); 
  for(var i=0;i<Imgs.length;i++){ 
    Imgs[i]=new Image(); 
    downloadImage(i); 
  } 
} 
//加载单个图片 
function downloadImage(i) 
{ 
  var imageIndex = i+1; //图片以1开始 
  Imgs[i].src = "images/"+imageIndex+".jpg"; 
  Imgs[i].onLoad=validateImages(i); 
} 
//验证是否成功加载完成，如不成功则重新加载 
function validateImages(i)
{ 
  if(!Imgs[i].complete) 
  { 
    window.setTimeout(‘downloadImage(‘+i+‘)‘,200);     
  } 
  else if(typeof Imgs[i].naturalWidth!="undefined"&&Imgs[i].naturalWidth==0) 
  { 
    window.setTimeout(‘downloadImage(‘+i+‘)‘,200); 
  } 
  else  
  { 
    ImgLoaded++ 
    if(ImgLoaded == Count) 
    { 
      document.getElementById(‘BtnStart‘).disabled=false; 
      document.getElementById(‘BtnStop‘).disabled=false; 
      alert(‘图片加载完毕！‘); 
    } 
  } 
} 
//开始 
function RandStart() 
{ 
  Init = setInterval(‘SetRand()‘,50);     
} 
//随机显示 
function SetRand() 
{ 
  imageIndex = Math.floor(Math.random()*Count); 
  document.getElementById("ImgView").src = Imgs[imageIndex].src; 
} 
//结束 
function RandStop() 
{ 
  window.clearInterval(Init); 
} 
</script>