下拉菜单到值输出

Question

下拉菜单到值输出

道歉,这看起来非常基本.我试图在输入字段中显示下拉列表的值.我一直在戳它几个小时,不能弄清楚我做错了什么.

function myFunction(){
         var e = document.getElementById("theDay");
         var dayValue = e.options[e.selectedIndex].value;
           document.getElementById("formValue").value = dayValue;
        }

Run Code Online (Sandbox Code Playgroud)

<!DOCTYPE html>
    <html lang="en">
    <body>
      <form action="" name="theForm">
        <select name="theDay" size="7">
          <option value="0">Monday</option>
          <option value="1">Tuesday</option>
          <option value="2">Wednesday</option>
          <option value="3">Thursday</option>
          <option value="4">Friday</option>
          <option value="5">Saturday</option>
          <option value="6">Sunday</option>
        </select>
      </form>
    <button onclick="myFunction()">Click me</button>
    to show drop down value <input type="text" id="formValue">
 
    </body>
    </html>

Run Code Online (Sandbox Code Playgroud)

Answer 1

Sha*_*lam 5

你错过了你的选择ID,所以替换

<select name="theDay" size="7">

Run Code Online (Sandbox Code Playgroud)

至

<select name="theDay" size="7" id="theDay">

Run Code Online (Sandbox Code Playgroud)

function myFunction(){
        var e = document.getElementById("theDay");
        var dayValue = e.options[e.selectedIndex].value;
        document.getElementById("formValue").value = dayValue;
    }

Run Code Online (Sandbox Code Playgroud)

<form action="" name="theForm">
    <select name="theDay" size="7" id="theDay">
        <option value="0">Monday</option>
        <option value="1">Tuesday</option>
        <option value="2">Wednesday</option>
        <option value="3">Thursday</option>
        <option value="4">Friday</option>
        <option value="5">Saturday</option>
        <option value="6">Sunday</option>
    </select>
</form>
<button onclick="myFunction()">Click me</button>
to show drop down value <input type="text" id="formValue">

Run Code Online (Sandbox Code Playgroud)

归档时间：	8 年，5 月前
查看次数：	68 次
最近记录：	8 年，5 月前