从另一个输入字段的下拉列表中自动获取值

Question

我有一个选择下拉菜单，可以从我公司不同部门的用户那里获取邮件。我想，当用户从下拉列表中选择部门名称时，部门的邮件地址将自动设置在下一个输入字段中。<select class="form-control" id="mail_type" name="email_to" onChange="getMailtype(this.value)" required>  <option value="[e-mail]" selected>Support</option>  <option value="[e-mail]">Billing</option>  <option value="[e-mail]">Sales</option> </select> <span id="mail_info"> <input type="text" name="email" class="form-control" value="[e-mail]" readonly>  </span>           所以，在这里我选择一个选项，电子邮件输入字段将使用 js 自动获取值

Answer 1

获取input并设置的值select

function getMailtype(value) {

  document.querySelector("#mail_info input").value = value;

}

<select class="form-control" id="mail_type" name="email_to" onChange="getMailtype(this.value)" required>

  <option value="[e-mail]" selected>Support</option>

  <option value="[e-mail]">Billing</option>

  <option value="[e-mail]">Sales</option>

</select>

<span id="mail_info">

 <input type="text" name="email" class="form-control" value="[e-mail]" readonly>

  </span>

Answer 2

const getMailtype = (target) => {

  $("#mail_info > input[name='email'")[0].value = target.value;

}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<select class="form-control" id="mail_type" name="email_to" onChange="getMailtype(this)" required>

  <option value="[e-mail]" selected>Support</option>

  <option value="[e-mail]">Billing</option>

  <option value="[e-mail]">Sales</option>

</select>

<span id="mail_info">

 <input type="text" name="email" class="form-control" value="[e-mail]" readonly>

  </span>