console 命令行工具 X clear
console
<!DOCTYPE html>
<html>

<head>
	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
	<title>demo</title>
	<style>
		ul,
		li {
			margin: 0;
			padding: 0;
		}

		body {
			font: 14px/1.5 Arial;
			color: #666;
		}

		#box {
			position: relative;
			width: 600px;
			height: 400px;
			border: 2px solid #000;
			margin: 10px auto;
			overflow: hidden;
		}

		#box ul {
			list-style-position: inside;
			margin: 10px;
		}

		#top,
		#bottom {
			color: #FFF;
			width: 600px;
			height: 200px;
			overflow: hidden;
		}

		#top {
			background: green;
		}

		#bottom {
			background: skyblue;
			position: absolute;
			/*float:right*/
		}

		#line {
			position: absolute;
			top: 50%;
			left: 0;
			height: 4px;
			width: 100%;
			overflow: hidden;
			background: red;
			cursor: s-resize;
		}
	</style>
</head>

<body>
	<center>上下拖动红条可改变显示区域宽度<span id="msg"></span></center>
<div id="box">
 <div id="top">
 上
 </div>
 <div id="bottom">
 下
 </div>
 <div id="line"></div>
</div>
 
<script>
function $(id) {
 return document.getElementById(id); 
}
window.onload = function() {
 var oBox = $("box"), oTop = $("top"), oBottom = $("bottom"), oLine = $("line");
 
 oLine.onmousedown = function(e) {
   var disY = (e || event).clientY;
   oLine.top = oLine.offsetTop;
 
   document.onmousemove = function(e) {
      var iT = oLine.top + ((e || event).clientY - disY);
      var e=e||window.event,tarnameb=e.target||e.srcElement;
      var maxT = oBox.clientHeight - oLine.clientHeight;
      oLine.style.margin = 0;
      iT < 0 && (iT = 0);
      iT > maxT && (iT = maxT);
      oLine.style.top = oTop.style.height = iT + "px";
      oBottom.style.height = oBox.clientHeight - iT + "px";
     $("msg").innerText='top.width:'+oLine.style.height+'---bottom.height:'+oBottom.style.height+'---oLine.offsetHeight:'+oLine.offsetHeight+'---disY:'+disY+'---tarnameb:'+tarnameb.tagName;
      return false
   }; 
 
   document.onmouseup = function() {
    document.onmousemove = null;
    document.onmouseup = null; 
    oLine.releaseCapture && oLine.releaseCapture()
   };
   oLine.setCapture && oLine.setCapture();
  return false
 };
};
</script>
</body>
</html>