JSFiddle - React, Tailwind, and code Playground

HTML

<select id="combo1" onchange="FlipOtherCombo(this, 'combo2')">
    <option value="yes">yes</option>
    <option value="no">no</option>
</select>
<select id="combo2" onchange="FlipOtherCombo(this, 'combo1')">
    <option value="yes">yes</option>
    <option selected="selected" value="no">no</option>
</select>

<script>
    function FlipOtherCombo(objCombo, strOtherComboId){
        if (objCombo.value ==="yes"){
            document.getElementById(strOtherComboId).value = "no";
        } else {
            document.getElementById(strOtherComboId).value = "yes";
        }
    }
</script>