你应该知道的兼容写法

1.滚动条

var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
console.log(scrollTop);
//如果要监听滚动条，监听onscroll事件即可
document.body.onscroll = function() {
  var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
  console.log(scrollTop);
}

2.获取样式兼容

function getStyle(dom, styleName){
  return dom.currentStyle?dom.currentStyle[styleName]getComputedStyle(dom)[styleName];
}

3.事件对象兼容

e  = e || window.event;

4.阻止事件冒泡兼容

event.stopPropagation? event.stopPropagation():event.cancelBubble=true;

5.阻止默认行为兼容

  function stopPreventDefault(e) {
        if (e && e.preventDefault) {
            e.preventDefault();//阻止浏览器默认行为(W3C) 
        } else {
           window.event.returnValue = false;//IE中阻止浏览器行为 
        }
        return false;
    }

6.事件监听兼容

 var addListen = function(element, name, fn) {
    if(element.addEventListener) {
        element.addEventListener(name, fn);
    }else if(element.attachEvent) {
        element.attachEvent('on' + name, fn);
    }else {
        element['on' + name] = fn; 
    }
}