How does jquery determine whether select is hidden?

two select, is a city drop-down choice, the first is a province choice, and the other is a city choice.
the city selection plug-in automatically hides the second one, which is displayed only when the selected province has a city.

the code is as follows: 


    <select></select>
    <select style="display: none;"></select> /**/

my question is how to determine how to add a class if select currently shows only one style without adding styles, if two

are displayed. Later, if you choose another province and there is no city to choose from, the previously added style in

will be removed. What should I do, please? Thank you very much! ~

Javascript jquery
Aug.29,2021 
<p id="select-box">
    <select id="province">
        <option value=""></option>
        <option value=""></option>
    </select>
    <select style="display: none;" id="city"></select>


<script>
    $(function(){
        var city = $('-sharpcity');
        $('-sharpprovince').change(function(){
            if(city.css('display')=='none'){
                $('-sharpselect-box').addClass('hasCity');
            }else{
                $('-sharpselect-box').removeClass('hasCity');
            }
        })
    })
</script>

Previous: About JSON.stringify ()

Next: Element ui table scrollTop scrolls to the beginning or end of a line

css mysql arrays josn react html typescript webpack npm sass R objective-c .net sql-server jquery python-3.x angularjs django angular excel regex iphone ajax linux xml pandas vba spring database wordpress string wpf xcode windows bash postgresql oracle multithreading eclipse list firebase algorithm macos forms image scala visual-studio azure bootstrap spring-boot react-native python-2.7 docker performance function winforms matlab powershell apache dataframe api sqlite numpy rest shell selenium flutter dart maven loops qt swing android-studio csv express file class tensorflow sorting codeigniter perl
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1e504fc-450be.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1e504fc-450be.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
Need Help?