React: Dropdown showing duplicate options than given

Question

For localization lang, I created a drropdown with two options Eng and Th (Thai). But While fetching the data, four options are showing for the same.

For example, if I select Thai, then 3 Thai options, and one Eng is showing, and vice versa for Eng also.As shown in figure

please help to figure it out.

My Selection code as follows:

    <select
         name="EN"
         id="EN"
         onChange={(e) => {
                      localStorage.setItem("lang", e.target.value);
                      window.location.reload(false);
                    }}
      >
         {localStorage.getItem("lang") !== null ? (
          <option selected={localStorage.getItem("lang")}>
             {localStorage.getItem("lang").toUpperCase()}
          </option>
            ) : null}
          <option value="en">EN</option>
          <option value="th">TH</option>
 </select>

Answer 1

The first one showing is the selected option you had wrote here:

<option selected={localStorage.getItem("lang")}>
             {localStorage.getItem("lang").toUpperCase()}
          </option>

The second one when you display the dropdown, is your selected one and I believe that's how the select element works by default. I don't know how to change that behavior.

Now, the third and fourth options are the ones you wrote here:

<option value="en">EN</option>
<option value="th">TH</option>

I would do something like:

{(localStorage.getItem("lang")) === en ? 
<option value="th">TH</option> : 
<option value="en">EN</option>)}

That way, you would only have the selected one, and the not selected one as options. The way you have wrote the code it will always show an EN and a TH option regardless the selected option.

Edit: after looking the code again, I don't understand why you fetch the selected lang as an option. It would be easier to just to:

 <select
         name="EN"
         id="EN"
         onChange={(e) => {
                      localStorage.setItem("lang", e.target.value);
                      window.location.reload(false);
                    }}
      >
       
          <option selected value="en">EN</option>
          <option value="th">TH</option>
 </select>

Also, i would rename the "name" and "id" of the select, to something like langSelector or anything like that and not having it related to a specific option, because that could change depending on the user decision.

If you really want to just have two options (actually one), I would look at this answer as a guide and make the placeholder a conditional based on the "lang" stored on your local storage, and the option would be a conditional too, like the example I already gave:

https://stackoverflow.com/a/30525521/14492009