JSFiddle - React, Tailwind, and code Playground

HTML

<select class="filtered remaining" id="multi-select-left" onChange="checkCode">
    <option cncode="0" value="1">User</option>
    <option parent="1" value="2">User-Login</option>
    <option parent="1" value="8">User-Logout</option>
    <option parent="1" value="11">User-Register</option>
    <option parent="0" value="3">Backend</option>
    <option parent="0" value="4">Settings</option>
    <option parent="4" value="5">Settings-Edit</option>
    <option parent="0" value="6">Category</option>
    <option parent="6" value="7">Category-add</option>
    <option parent="0" value="12">logger</option>
    <option parent="0" value="13">brands</option>
    <option parent="0" value="14">User-Role</option>
</select>
<input type="text" id="sub">

JavaScript

$('#multi-select-left').change( function() {
    var $t = $(this);    
    var tVal = $t.val();    
    var tParent = $t.find('option:selected').attr('cncode');

    alert( 'tVal: ' + tVal);
    alert( 'cncode : ' + tParent );
    document.getElementById("sub").value = tParent;
    });
    
    function checkCode(){
    document.getElementById("sub").value = document.getElementById("#multi-select-left").value;
    }