Javascript 按下“一次更新”按钮后可选择多个选项

Javascript 按下“一次更新”按钮后可选择多个选项,javascript,Javascript,在下面的示例代码中,当按下“添加章节”按钮时,应添加章节(提示用户输入章节标题)。有两个地方需要将新的chapter元素插入DOM 但是,当按下“添加章节”按钮时,在提示框中输入值后会显示错误 有人能帮我吗 <html> <body> <form> <div id="mainsec1" style="border: 1pt solid; width: 40%;padding: 10pt"> <div i

在下面的示例代码中,当按下“添加章节”按钮时,应添加章节(提示用户输入章节标题)。有两个地方需要将新的chapter元素插入DOM

但是,当按下“添加章节”按钮时,在提示框中输入值后会显示错误

有人能帮我吗

<html>
  <body>
    <form>
      <div id="mainsec1" style="border: 1pt solid; width: 40%;padding: 10pt">
        <div id="sec1">
          <span class="head1">Chapter</span>
            
          <select name="startype" id="starselect">
            <option selected="selected" />
            <option value="Aquila">Aquila</option>
            <option value="Centaurus">Centaurus</option>
            <option value="Canis Major">Canis Major</option>
          </select>
          <span class="head1">
            <input type="button" class="buttonit" value="Delete" onclick="Delerow();" />
          </span>
        </div>
        <div id="sec2">
          <span class="head1">Heading</span>

          <select name="startypeHead" id="starheading">
            <option selected="selected" />
            <option value="Aquila">Aquila Heading</option>
            <option value="Centaurus">Centaurus Heading</option>
            <option value="Canis Major">Canis Major Heading</option>
          </select>
          <span class="head1">
            <input type="button" class="buttonit" value="Delete" onclick="Delerowsub();" />
          </span>
        </div>
        <input type="button" class="buttonit" value="Add Heading" onclick="AddHead();" />
      </div>
      <div id="mainsec2" style="margin-top: 10pt;border: 1pt solid; width: 40%;padding: 10pt">
        <div id="sec3">
          <span class="head1">Chapter</span>

          <select name="startypechap" id="starselectchap">
            <option selected="selected" />
            <option value="Aquila">Aquila Chapter</option>
            <option value="Centaurus">Centaurus Chapter</option>
            <option value="Canis Major">Canis Major  Chapter</option>
          </select>
          <span class="head1">
            <input type="button" class="buttonit" value="Delete" onclick="Delerow();" />
          </span>
        </div>
      </div>
      <input type="button" class="buttonitonsub" value="Add Chapter" onclick="AddChap();" />
    </form>
  <script>
    var glovar;
    document.getElementById('starselect').onchange = function(){
      var list = document.forms[0].startype;
      glovar = list.selectedIndex;
      var sublist = document.forms[0].startypeHead;
      sublist.selectedIndex = glovar;
    }
    function AddHead(){
      var inpVal = prompt("Input your Heading", "Heading");
      var select = document.getElementById("starheading"); 
      var opele = document.createElement("option");
      opele.value = inpVal;
      opele.text = inpVal;
      select.add(opele);
    }
    function AddChap(){
      var inpVal=prompt("Input your Chapter", "Chapter");
      var select = document.getElementById("starselectchap"); 
      var select1 = document.getElementById("starselect"); //Here, I am trying to get the required element.
      var opele = document.createElement("option");
      opele.value = inpVal;
      opele.text = inpVal;
      select.add(opele);
      alert(select1.add(opele));
    }
  </script>
  </body>
</html>

章
 
阿奎拉
半人马座
大犬
标题
阿奎拉穗
半人马座航向
犬科大类
章
阿奎拉章
半人马座章节
犬大部
格洛瓦变种;
document.getElementById('starselect')。onchange=function(){
var list=document.forms[0].startype;
glovar=list.selectedIndex;
var sublist=document.forms[0]。星形字体;
sublist.selectedIndex=glovar;
}
函数AddHead(){
var inpVal=提示(“输入标题”、“标题”);
var select=document.getElementById(“starheading”);
var opele=document.createElement(“选项”);
opele.value=inpVal;
opele.text=inpVal;
选择。添加(OPLE);
}
函数AddChap(){
var inpVal=提示(“输入您的章节”、“章节”);
var select=document.getElementById(“starselectchap”);
var select1=document.getElementById(“starselect”);//在这里,我试图获取所需的元素。
var opele=document.createElement(“选项”);
opele.value=inpVal;
opele.text=inpVal;
选择。添加(OPLE);
警报(选择1.添加(操作));
}

这里是一个可以尝试的方法。

因为您要将新创建的DOM元素添加到第一个select中,所以无法将其添加到第二个select中。您需要创建两个元素来添加到DOM中:

var inpVal=prompt("Input your Chapter", "Chapter");
var select = document.getElementById("starselectchap"); 
var select1 = document.getElementById("starselect"); // Here, I am trying to get the required element.
var opele = document.createElement("option");
opele.value = inpVal;
opele.text = inpVal;
var opele1 = document.createElement("option");
opele1.value = inpVal;
opele1.text = inpVal;
// Or use opele.cloneNode(), depending on your browser support.
select.add(opele);
select1.add(opele1);
这将解决问题。我真的建议您运行JavaScript代码