JSFiddle - React, Tailwind, and code Playground

by André Albson

HTML

<select id="orgAssign" multiple="true">
   <option selected="" value="10047">test1</option>
   <option selected="" value="10046">test2</option>
   <option value="10033">test3</option>
   <option value="10032">test4</option>
</select>

JavaScript

$('select').on({
    mousedown: function(e) {
        $(this).data('sel', $('option:selected', this));
        $(this).data('flag', $(e.target).prop('selected'));
    },
    mouseup: function(e) {
        $(this).data('sel').not(e.target).prop('selected', true);
        $(e.target).prop('selected', !$(this).data('flag'));
    }
});