How to make multi level dropdown menu using select option mentod

问题

i want to make multi level dropdown menu using select and option method

<select>
   <option value="" data-display-text="Select">None</option>
   <option value="oranges">SSC</option>
   <option value="oranges">GATE</option>
   <option value="bananas">BANK PO</option>
   <option value="bananas">RAILWAY</option>
 </select>

回答1:

As far as I understand your "multi level dropdown" concept You can make simple dropdown and just move some elements by css. Cathegory name is stored in optogroup.

<select name="select_projects" id="select_projects">
        <option value="">project.xml</option>
        <optgroup label="client1">
            <option value="">project2.xml</option>
        </optgroup>
        <optgroup label="client2">
            <option value="">project5.xml</option>
            <option value="">project6.xml</option>
            <optgroup label="client2_a">
                <option value="" style="margin-left:23px;">project7.xml</option>
                <option value="" style="margin-left:23px;">project8.xml</option>
            </optgroup>
            <option value="">project3.xml</option>
            <option value="">project4.xml</option>
       </optgroup>
       <option value="">project0.xml</option>
       <option value="">project1.xml</option>
    </select>

Updated:
Or if you are trying to make a "chain" of dropdowns like you have in start menu in windows, that is the easiest way to do it:
https://jqueryui.com/menu/

回答2:

If you want to use ONE select you could use <optgroup/>. See example. Note: it's not very multi-level, but it allows for some kind of relevant grouping.

<select>
  <option value="" selected="selected">Select an option...</option>
  <optgroup label="SSC">
    <option value="oranges1">some option</option>
    <option value="oranges2">some option</option>
    <option value="oranges3">some option</option>
  </optgroup>
  <optgroup label="GATE">
    <option value="bananas1">some option</option>
    <option value="bananas2">some option</option>
    <option value="bananas3">some option</option>
  </optgroup>
  <optgroup label="BANK PO">
    <option value="apples1">some option</option>
    <option value="apples2">some option</option>
    <option value="apples3">some option</option>
  </optgroup>
  <optgroup label="RAILWAY">
    <option value="grapes1">some option</option>
    <option value="grapes2">some option</option>
    <option value="grapes3">some option</option>
  </optgroup>
</select>

回答3:

You can't make multiple levels with the select element.

In this case you would create a custom component with the capability to display something like 'hierarchic'.

Or use the trick like this:

<select>
    <option>select me</option>
    <option>&nbsp;me indented</option>
    <option>&nbsp;&nbsp;even more indentation</option>
</select>

回答4:

You can't make multiple levels with the select element.

Any ways, if its any help, there's

<select>
  <optgroup label="Swedish Cars">
    <option value="volvo">Volvo</option>
    <option value="saab">Saab</option>
  </optgroup>
  <optgroup label="German Cars">
    <option value="mercedes">Mercedes</option>
    <option value="audi">Audi</option>
  </optgroup>
</select>

来源：https://stackoverflow.com/questions/44367357/how-to-make-multi-level-dropdown-menu-using-select-option-mentod

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