css响应有media，js响应有这种

比如，我不想在移动端执行某js特效可以参考
(function(doc, win) {
    var screenWidth = 0, size = 'M', root = doc.documentElement;
    if (window.screen && screen.width) {
        screenWidth = screen.width;
        if (screenWidth > 1920) {
            // 超大屏，例如iMac
            size = 'L';
        } else if (screenWidth < 480) {
            // 小屏，如手机
            size = 'S';
        }
    }
    // 标记CSS
    root.className = size;
    // 标记JS
    win.SIZE = size;        
})(document, window);


目前做的实例运用中
<script>
      (function(doc, win) {
    var screenWidth = 0, size = 'M', root = doc.documentElement;
    if (window.screen && screen.width) {
        screenWidth = screen.width;
        if (screenWidth > 768) {
          //悬浮 效果就是滚动大1的时候，延迟2.5s执行js效果且只让这效果执行一次
              $(function(){
                  function haha(){ 
                  var scrollTop =  document.body.scrollTop || document.documentElement.scrollTop;
                    if(scrollTop >1){              
                            $('.lis2').show(1000);                
                            }                     
                  }
                  var tur = true;
                  window.onscroll = function(){
                      if(tur){ setTimeout(haha,2500); tur = false; } 
                  }
                  
                })
               
             $(function(){
                  $('.xfbut').click(function(){
                    $('.lis2').hide();
                  })
                })
        } else if (screenWidth < 767) {
            // 小屏，如手机
            size = 'S';
        }
    }
    // 标记CSS
    root.className = size;
    // 标记JS
    win.SIZE = size;        
})(document, window);
    </script>
这个可以完满解决在767尺寸之外执行那段js特效
具体的参考http://www.zhangxinxu.com/wordpress/2016/06/pseudo-response-layout-base-on-screen-width/comment-page-1/#comment-319478