Javascript：将 HTML <select> 存储为变量？

Javascript: Store HTML <select> as a variable?

提问by user2642359

The HTML:

HTML：

      <select id="selected2">
          <option selected>1</option>
          <option>2</option>
          <option>3</option>
      </select>

      <select id="selected2">
          <option selected>1</option>
          <option>2</option>
          <option>3</option>
      </select>

I've tried using this code in JavaScript:

我曾尝试在 JavaScript 中使用此代码：

var dataCap = document.getElementById("selected2");

var userSelect = dataCap.options[dataCap.selectedIndex].text;

var dataCap = document.getElementById("selected2");

var userSelect = dataCap.options[dataCap.selectedIndex].text;

But console says: "TypeError: dataCap is null"

但控制台说：“TypeError：dataCap 为空”

回答by Jacques ジャック

You need the set a value for each option:

您需要为每个选项设置一个值：

<select id="selected2">
      <option selected value=""></option>
      <option value="2">2</option>
      <option value="3">3</option>
  </select>

The text between the tags is just for the user to see, but does not return the value.

标签之间的文字仅供用户查看，不返回值。

Also, your javascript variable should read:

此外，您的 javascript 变量应为：

var dataCap = document.getElementById("selected2").value;

I added .valueto the end so it knows to get the value.

我添加.value到最后，所以它知道获取值。