text: $.fn.stick =function(){
  	var $cur = this,
  		curH = $cur.height(),
  		curW = $cur.width(),
  		offsetTop = $cur.offset().top,
  		offsetLeft = $cur.offset().left,
  		isFixed = false;
  
  	//  克隆元素，用于占位
  	var $curClone = $cur.clone()
  						.css({visibility: "hidden",display: "none"})
  						.insertBefore($cur);
  	
  
  	//  设置监听函数
  	$(window).on("scroll", function(){
  		var winScroll = $(this).scrollTop();
  		if(offsetTop < winScroll){
  			if(!isFixed){
  				setFixed();
  			}
  		}else{
  			if(isFixed){
  				unsetFixed();
  			}
  		}
  	});
  
  
  
  	// 设置添加和删除stick函数
  	function setFixed(){
  		$cur.css({
  			"position" : "fixed",
  			"top" : 0,
  			"left" : offsetLeft,
  			"width" : curW,
  			"z-index" : 100,
  			"margin" : 0
  		}),
  		$curClone.show();
  		isFixed = true;
  	}
  	function unsetFixed(){
  		$cur.removeAttr("style");
  		$curClone.hide();
  		isFixed = false;
  	}
  
  }