<script language="javascript"> function check(){ s.disabled=(t1.value==""||t2.value==""||t3.value=="") } </script> <input name="t1" onpropertychange="check()" /> <input name="t2" onpropertychange="check()" /> <input name="t3" onpropertychange="check()" /> <input type="submit" name="s" disabled="desabled" />
[Ctrl+A 全部选择 提示：你可先修改部分代码，再按运行]
