js-事件委托&图片预加载

事件委托

$(function (){
    var oUl=document.getElementById('ul1');
    oUl.onclick=function (ev){
        var oEvent=ev || event;
        var oSrc=oEvent.srcElement || oEvent.target;
        if (oSrc.tagName == 'LI')
        {
            oSrc.style.background='red';
        }
    };
});

window.navigator.userAgent.indexOf('MSIE 6.0') != -1

图片预加载

window.onload=window.onscroll=window.onresize=function (){
    var aImg=document.getElementsByTagName('img');
    var scrollTop=document.documentElement.scrollTop || document.body.scrollTop;
    var clientHeight=document.documentElement.clientHeight;
    var clientBottom=clientHeight+scrollTop;
    for (var i=0; i<aImg.length; i++)
    {
        if (aImg[i].offsetTop <= clientBottom)
        {
            // 在可视区内
            var _src=aImg[i].getAttribute('_src');
            aImg[i].src=_src;
        }
    }
};

吸顶条

window.onload=function (){
    var oDiv=document.getElementById('div1');
    var oDiv2=document.getElementById('div2');
    var top=oDiv.offsetTop;
    window.onscroll=function (){
        var scrollTop=document.documentElement.scrollTop || document.body.scrollTop;
        if (top <= scrollTop)
        {
            // 吸顶
            oDiv.style.position='fixed';
            oDiv2.style.display='block';
        }
        else
        {
            // 不吸
            oDiv.style.position='';
            oDiv2.style.display='none';
        }
    };
};

图片预加载

window.onload=function (){
    var oDiv=document.getElementById('div1');
    var oSpan=document.getElementById('span1');
    var total=77; // 总数
    var n=0; // 当前加在张数
    for (var i=0; i<total; i++)
    {
        var oImg=new Image();
        oImg.src='[http://www.zhinengshe.com/works/3525/img/](http://www.zhinengshe.com/works/3525/img/)'+i+'.jpg';
        oImg.onload=function (){
            n++;
            // 0 - 1
            var scale=n/total*100;
            oSpan.innerHTML=Math.floor(scale)+'%';
            oDiv.style.width=scale+'%';
        };
    }
};
 // [http://www.zhinengshe.com/works/3525/img/0.jpg](http://www.zhinengshe.com/works/3525/img/0.jpg)
 // 76