JSFiddle - React, Tailwind, and code Playground

HTML

<select id="left" >
    <option value="">--</option>
    <option value="1">1</option>
    <option value="2">2</option>
    <option value="3" data-display="0" selected="true" >3</option>
    <option value="4" data-display="0">4</option>
    <option value="5">5</option>
</select>
<select id="right">
    <option value="">--</option>
    <option value="1">1</option>
    <option value="2">2</option>
    <option value="3">3</option>
    <option value="4">4</option>
    <option value="5">5</option>
</select>

JavaScript

$(document).ready(function() {
    
    var left = $("#left");
    var right = $("#right");
    
    left.change(function(){
    			var selectedOption = $(this).find("option[data-display='0']");
          if (selectedOption != null)
          {
 							alert(selectedOption.length);
					}
          
    });
    
    right.change(function() {
        if (left.val() == $(this).val()) {
            alert("error");
            $(this).attr("selectedIndex", "0");
        }
    });
});