<html>
    <head>
        <meta charset=utf-8>
    </head>
    <body>
    	<input id="input"  onchange="handcnange(this);" type="text" />
        <span id="span"></span>

        <script type="text/javascript">
            // 补全代码
         function handcnange(obj){
			 document.getElementById('span').innerHTML = obj.value;
         } 
        </script>
    </body>
</html>