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纯JS图片批量预加载技术代码

  作者：bea

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>图片批量加载</title>
</head>
<body>
<div id="status" ></div>
<div id="processing"></div>
<script type="text/javascript">
function $id(id){ return document.getElementById(id);}
function $c(tagName){ return document.createElement(tagName);}
window.onload = function(){
imageLoad( {
url:function(v){
v = [];
for(var i=1; i<=8; i++){
v[v.length] = 'http://files./demoimg/200911/wall_s'+i+'.jpg?_='+(new Date).getTime();
}
return v;
},
oncomplete: function(s){
$id('status').innerHTML = '正在加载...'+s.complete+'/'+s.total;
$id('processing').innerHTML = this.src;
},
complete:function(imgs, s){
var $r = $c('div');
$r.id = 'result';
$r.innerHTML = '计划加载:'+s.total+', 加载成功:'+s.load+'错误:'+s.error;
document.body.appendChild($r);
for(var i=0, l=imgs.length, $m; i<l; i++){
$m = $c('div');
$m.innerHTML = (imgs[i].loaded?'加载成功:':'加载失败:')+ imgs[i].src;
document.body.appendChild($m);
}
}
});
};
function imageLoad( s ){
var urlset = [], undefined, toString = Object.prototype.toString;
switch( toString.apply(s.url) ){
case '[object String]': urlset[urlset.length] = s.url; break;
case '[object Array]': if(!s.url.length){ return false; } urlset = s.url; break;
case '[object Function]': s.url = s.url(); return imageLoad( s );
default: return false;
}
var imgset =[], r ={ total:urlset.length, load:0, error:0, abort:0, complete:0, currentIndex:0 }, timer,
_defaults = {
url:'',
onload: 'function',
onerror: 'function',
oncomplete: 'function',
ready: 'function',
complete: 'function',
timeout: 15
};
for( var v in _defaults){
s[v] = s[v]===undefined? _defaults[v]: s[v];
}
s.timeout = parseInt( s.timeout ) || _defaults.timeout;
timer = setTimeout( _callback, s.timeout*1000);
for( var i=0,l=urlset.length,img; i<l; i++){
img = new Image();
img.loaded = false;
imgset[imgset.length] = img;
} for( i=0,l=imgset.length; i<l; i++){
imgset[i].onload = function(){ _imageHandle.call(this, 'load', i ); };
imgset[i].onerror = function(){ _imageHandle.call(this, 'error', i ); };
imgset[i].onabort = function(){ _imageHandle.call(this, 'abort', i ); };
imgset[i].src = ''+urlset[i];
}
if( _isFn(s.ready) ){ s.ready.call({}, imgset, r); }
function _imageHandle( handle, index ){
r.currentIndex = index;
switch( handle ){
case 'load':
this.onload = null; this.loaded = true; r.load++;
if( _isFn(s.onload) ){ s.onload.call(this, r); }
break;case 'error': r.error++;
if( _isFn(s.onerror) ){ s.onerror.call(this, r); }
break;
case 'abort': r.abort++; break;
}
r.complete++;
// oncomplete 事件回调
if( _isFn(s.oncomplete) ){ s.oncomplete.call(this, r); }
// 判断全局加载
if( r.complete===imgset.length ){ _callback(); }
}
function _callback(){
clearTimeout( timer );
if( _isFn(s.complete) ){ s.complete.call({}, imgset, r); }
}
function _isFn(fn){ return toString.apply(fn)==='[object Function]'; }
return true;
}
</script>
</body>
</html>




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