下拉隐藏值

我希望1的日值仅在用户选择一个月而不是空白值时显示，但它不工作......我认为该函数是错误的。我希望当天的下拉菜单中只有在没有选择月份时才显示。请帮助我....下拉隐藏值

<html> 
<head> 
<script type="text/javascript"> 
function show(x) { 
var mon = document.getElementById(x).innerHTML 
if (mon == "") { 
document.getElementById("one").style.display="none"; 
} else { 
document.getElementById("one").style.display=""; 
} 
} 
</script> 

</head> 

<body> 
Calendar<br> 
<hr align="left" width="200px"/> 


--Year ------ Month ----- Day<br> 
<select name="year"> 
<option value="defaulty"></option> 
<option value="2012">2012</option> 
<option value="2013">2013</option> 
<option value="2014">2014</option> 
<option value="2015">2015</option> 
</select> 

<select name="month" onchange="show(this)"> 
<option id="defaultm"></option> 
<option id="January">January</option> 
<option id="February">February</option> 
<option id="March">March</option> 
<option id="April">April</option> 
<option id="May">May</option> 
<option id="June">June</option> 
<option id="July">July</option> 
<option id="August">August</option> 
<option id="September">September</option> 
<option id="October">October</option> 
<option id="November">November</option> 
<option id="December">December</option> 
</select> 

<select name="day"> 
<option id="defaultd" value="defaultd"></option> 
<option id="one" value="one" style="display:none">1</option> 

</select> 

</body> 

</html>

来源

2012-08-13 John Doe

所以，你希望当天的专栏只有在月份选择正确时才可用？如果我正确地理解你，这将会成功。

<html> 
<head> 
    <script type="text/javascript"> 

     function show() { 

      if (document.getElementById("month").selectedIndex != 0) { 
       document.getElementById("day").disabled = false; 
      } 
      else { 
       document.getElementById("day").disabled = true; 
      } 
     } 
    </script> 
</head> 
<body> 

    Calendar<br> 
    <hr align="left" width="200px"/> 
    <form actn=""> 
     --Year ------ Month ----- Day<br> 
     <select name="year" id="year"> 
      <option value="defaulty"></option> 
      <option value="2012">2012</option> 
      <option value="2013">2013</option> 
      <option value="2014">2014</option> 
      <option value="2015">2015</option> 
     </select> 
     <select name="month" id="month" onchange="show()"> 
      <option value="defaultm"></option> 
      <option value="January">January</option> 
      <option value="February">February</option> 
      <option value="March">March</option> 
      <option value="April">April</option> 
      <option value="May">May</option> 
      <option value="June">June</option> 
      <option value="July">July</option> 
      <option value="August">August</option> 
      <option value="September">September</option> 
      <option value="October">October</option> 
      <option value="November">November</option> 
      <option value="December">December</option> 
     </select> 
     <select name="day" id="day" disabled="disabled"> 
      <option id="defaultd" value="defaultd"></option> 
      <option id="one" value="one">1</option> 
     </select> 
    </form> 
</body>

来源

2012-08-13 19:47:45 Jeremy1026

回答

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