下拉菜单既可以选择,又可以自己填写
按回车键输入新内容，按DEL删除选中内容
<body bgcolor="#fef4d9" onload="s1.focus();"> <script language="JavaScript"> <!-- function catch_keydown(sel) { switch(event.keyCode) { case 13: //Enter; sel.options[sel.length] = new Option("","",false,true); event.returnValue = false; break; case 27: //Esc; alert("text:" + sel.options[sel.selectedIndex].text + ", value:" + sel.options[sel.selectedIndex].value + ";"); event.returnValue = false; break; case 46: //Delete; if(confirm("删除当前选项!?")) { sel.options[sel.selectedIndex] = null; if(sel.length>0) { sel.options[0].selected = true; } } event.returnValue = false; break; case 8: //Back Space; var s = sel.options[sel.selectedIndex].text; sel.options[sel.selectedIndex].text = s.substr(0,s.length-1); event.returnValue = false; break; } } function catch_press(sel) { sel.options[sel.selectedIndex].text = sel.options[sel.selectedIndex].text + String.fromCharCode(event.keyCode); event.returnValue = false; } //--> </script> <select name=s1 onkeydown="catch_keydown(this);" onkeypress="catch_press(this);" style="font-size:12px;"><option>---</option></select>详细出处参考：http://www.jb51.net/article/411.htm