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 = 1; //每次滚动的间距, 越大滚动越快
var ipath = '/common/imgs/'; //图片路径
var thumbs = document.getElementsByClassName('thumb_img');

for (var i=0; i<thumbs.length; i++) {
    thumbs[i]. = function () {
        $('#main_img').attr("src",$(this).attr("rel"));
        $('#main_img').attr("link",$(this).attr("link"));
    };
//    thumbs[i].onclick = function () {
//        location = this.link
//    }
}

$('#main_img').click(function () {
//    location = this.link;
});

$('#gotop').mouseover(function() {
   
    $(this).attr("src",ipath + 'gotop2.gif');
    MyMar=setInterval(gotop,speed);
});
$('#gotop').mouseout(function() {
   
    $(this).attr("src",ipath + 'gotop.gif');
    clearInterval(MyMar);
});

$('#gobottom').mouseover(function() {
   
    $(this).attr("src",ipath + 'gobottom2.gif');
    MyMar=setInterval(gobottom,speed);
});
$('#gobottom').mouseout(function() {
   
    $(this).attr("src",ipath + 'gobottom.gif');
    clearInterval(MyMar);
});
function gotop() {
    window.document.getElementById('showArea').scrollTop-=spec;
//    $('#showArea').attr("scrollTop",spec--);
};
function gobottom() {
    window.document.getElementById('showArea').scrollTop+=spec;
//    $('#showArea').attr("scrollTop",spec++);
};