如何从Bootstrap 4的下拉菜单中获取价值？

Question

<li class="nav-item dropdown">
                <a class="nav-link dropdown-toggle toggle2" href="#" id="navbarDropdown2" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                    Material Type
                </a>


                <div class="dropdown-menu menu2" aria-labelledby="navbarDropdown2">
                    <a class="dropdown-item">Mud</a>
                    <div class="dropdown-divider"></div>
                    <a class="dropdown-item">Cloth</a>
                    <div class="dropdown-divider"></div>
                    <a class="dropdown-item">Thread</a>
                    <div class="dropdown-divider"></div>
                    <a class="dropdown-item">Jute</a>
                    <div class="dropdown-divider"></div>
                    <a class="dropdown-item">Cotton</a>
                    <div class="dropdown-divider"></div>
                    <a class="dropdown-item">Cane</a>
                    <div class="dropdown-divider"></div>
                    <a class="dropdown-item">Bamboo</a>
                </div>
            </li>

Can I get the value from the menu after selecting like following?

var email=document.getElementById('signUpEmail').value;

So that I can use this variable in ajax.

Edit
As @Timir suggest to use select then the menu is look like

<li class="nav-item">
<select class="custom-select custom-select-lg mb-3" id="mydropdown">
  <option selected>Material Type</option>
  <option value="Mud">Mud</option>
  <option value="Cloth">Cloth</option>
  <option value="Thread">Thread</option>
  <option value="Jute">Jute</option>
  <option value="Cotton">Cotton</option>
  <option value="Can">Can</option>
  <option value="Bamboo">Bamboo</option>
</select>
</li>

Answer 1

Can I get the value from the menu after selecting like following?

No, there are no input to retrieve their value. but you can get the text inside the link like

$('.menu2 a.dropdown-item').on('click', function(){
    $(this).text()
});

Answer 2

把它变成一个选择，给它一个ID，然后说： $(“#mydropdown option:selected”).val();

Answer 3

There are workarounds for basically everything in JavaScript. Including this. Without using JQuery, you could add an event listener, or you could make an onlick within each option or anchor tag. When you click on the drop down and set the option, it calls the function which sets the variable. So even though there is no input box... you are just setting a global variable. And then you utilize that variable as a part of a form or however you plan on using it.