JSFiddle - React, Tailwind, and code Playground

HTML

<form id="frm_">
    <select name="Veh" onchange="getRep()">
        <option value='-1' selected='selected'>Select</option>
        <option value='0' ren='x'>xxx</option>
        <option value='1' ren='y'>yyy</option>
    </select>
</form>

JavaScript

function getRep() {
    var ren = document.forms['frm_'].elements['Veh'].options[document.forms['frm_'].elements['Veh'].selectedIndex].getAttribute('ren');

    console.log("Val of ren " + ren); //x or y

}