//javascript Document
function chinaz(){
    this.init();
}
chinaz.prototype = {
    constructor: chinaz,
    init: function(){
        this._initBackTop();
    },
    _initBackTop: function(){
        var $backTop = this.$backTop = $('<div class="cbbfixed">'+
        '<a class="gotop cbbtn">'+
        '<span class="up-icon"></span>'+
        '</a>'+
        '</div>');
        $('body').append($backTop);

        $backTop.click(function(){
            $("html, body").animate({
                scrollTop: 0
            }, 120);
        });

        var timmer = null;
        $(window).bind("scroll",function() {
            var d = $(document).scrollTop(),
                e = $(window).height();
            0 < d ? $backTop.css("bottom", "10px") : $backTop.css("bottom", "-90px");
            clearTimeout(timmer);
            timmer = setTimeout(function() {
                clearTimeout(timmer)
            },100);
        });
    }

}
var chinaz = new chinaz();