兼容ie8 ff ie6获取窗口顶部与左边像素代码

 _browser_scroll_x = 0;
    _browser_scroll_y = 0;
    if( typeof( window.pageyoffset ) == 'number' )
    {
        //netscape compliant
        _browser_scroll_y = window.pageyoffset;
        _browser_scroll_x = window.pagexoffset;
    } else if( document.body && ( document.body.scrollleft || document.body.scrolltop ) )
    {
        //dom compliant
        _browser_scroll_y = document.body.scrolltop;
        _browser_scroll_x = document.body.scrollleft;
    }
    else if( document.documentelement && ( document.documentelement.scrollleft || document.documentelement.scrolltop ) )
    {
        //ie6 standards compliant mode
        _browser_scroll_y = document.documentelement.scrolltop;
        _browser_scroll_x = document.documentelement.scrollleft;
    }