function $(e) {return document.getElementById(e);}
document.getElementsByClassName = function(cl) {
    var retnode = [];
    var myclass = new RegExp('\\b'+cl+'\\b');
    var elem = this.getElementsByTagName('*');
    for (var i = 0; i < elem.length; i++) {
        var classes = elem[i].className;
        if (myclass.test(classes)) retnode.push(elem[i]);
    }
    return retnode;
}
var MyMar;
var speed = 1; //速度，越大越慢
var spec = 2; //每次滚动的间距, 越大滚动越快
var ipath = 'images/'; //图片路径
var thumbs = document.getElementsByClassName('thumb_img');
for (var i=0; i<thumbs.length; i++) { 
    thumbs[i].onclick = function () {location = this.link}
	
}

$('main_img').onclick = function () {location = this.link;}

$('gotop').onmouseover = function() {this.src = ipath + 'gotop2.gif'; MyMar=setInterval(gotop,speed);}
$('gotop').onmouseout = function() {this.src = ipath + 'gotop.gif'; clearInterval(MyMar);}
$('gobottom').onmouseover = function() {this.src = ipath + 'gobottom2.gif'; MyMar=setInterval(gobottom,speed);}
$('gobottom').onmouseout = function() {this.src = ipath + 'gobottom.gif'; clearInterval(MyMar);}
function gotop() {$('showArea').scrollTop-=spec;}
function gobottom() {$('showArea').scrollTop+=spec;}