//1.滚动条到顶端的距离(滚动高度)
var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
//2.滚动条到左端的距离
var scrollLeft = document.documentElement.scrollLeft || document.body.scrollLeft;
//3. IE9以下byClassName
function byClassName(obj,className){
    //判断是否支持byClassName
    if(obj.getElementsByClassName){
        //支持
        return obj.getElementsByClassName(className);
    }else{
        //不支持
        var eles = obj.getElementsByTagName('*'); //获取所有的标签
        var arr = []; //空数组,准备放置找到的对象
        //遍历所有的标签
        for(var i = 0,len = eles.length;i < len;i ++){
            //找出与我指定class名相同的对象
            if(eles[i].className === className){
                arr.push(eles[i]); //存入数组
            }
        }
        return arr; //返回
    }
}
//4. 获取非行内样式兼容
function getStyle(obj,attr){
    return window.getComputedStyle ? getComputedStyle(obj,true)[attr] : obj.currentStyle[attr];
}
//5. 获取事件对象的兼容
evt = evt || window.event
//6. 获取鼠标编码值的兼容
function getButton(evt){
    var e = evt || window.event;
    if(evt){
        return e.button;
    }else if(window.event){
        switch(e.button){
            case 1 : return 0;
            case 4 : return 1;
            case 2 : return 2;
        }
    }
}
//7. 获取键盘按键编码值的兼容
var key = evt.keyCode || evt.charCode || evt.which;
//8. 阻止事件冒泡的兼容      非IE                     IE
e.stopPropagation ? e.stopPropagation() : e.cancelBubble = true;
//9. 阻止超链接的默认行为的兼容
evt.preventDefault ? evt.preventDefault() : evt.returnValue = false;
//10. 添加事件监听器的兼容
function addEventListener(obj,event,fn,boo){
    if(obj.addEventListener){
        obj.addEventListener(event,fn,boo);
    }else if(obj.attachEvent){
        obj.attachEvent('on' + event,fn);
    }
}
//11. 移除事件监听器的兼容
function removeEventListener(obj,event,fn,boo){
    if(obj.removeEventListener){
        obj.removeEventListener(event,fn,boo);
    }else if(obj.detachEvent){
        obj.detachEvent('on' + event,fn);
    }
}
//12. 获取事件源的兼容
var target = event.target || event.srcElement;
//13.防止默认拖拽行为
document.ondragstart = function(){
                        return false;
                    }
//14.创建Ajax对象的兼容(IE6)
    var xhr = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHTTP')