图片延迟加载

window.onload=window.onresize=window.onscroll=function()
{
showImg();
};

function getPos(obj)
{
var l=0;
var t=0;

while(obj)
{
l+=obj.offsetLeft;
t+=obj.offsetTop;

obj=obj.offsetParent;
}

return {left: l, top: t};
}
function showImg()
{
var aTmg=document.getElementsByTagName('img');
var scrollTop=document.documentElement.scrollTop||document.body.scrollTop;
var scrollBottom=scrollTop+document.documentElement.clientHeight;

for(var i=0;i<aTmg.length;i++)
{
var p=getPos(aTmg[i]);
if(p.top<scrollBottom)
{
//alert(aTmg);
aTmg[i].src=aTmg[i].getAttribute('_src');
}
}
}