不同浏览器应用scrollTop属性

window.onscroll = _onScroll;function _onScroll(){

    var aside = document.getElementsByClassName('aside')[0];    var scrollTop = document.documentElement.scrollTop  //在ie下                    +document.body.scrollTop ;//其他浏览器    if(scrollTop>230){        aside.style.position='fixed'        aside.style.top ='0px'    }else{        aside.style.position='absolute'        aside.style.top ='230px'    }    console.log(scrollTop)

};