JSFiddle - React, Tailwind, and code Playground

by artwl

HTML

<div class="fieldinput" id="disney">
    <label for="disney">Disney Character</label>
    <select name="disney">
        <option value="">Choose...</option>
        <option value="mickey">Mickey Mouse</option>
        <option value="mini">Mini Mouse</option>
    </select>
</div>
<input type="button" value="submit" id="btnSub" />

JavaScript

function validate(disney) {
    var result = !! disney;
    if (!result) {
        alert("An option must be selected.\n");
    }
    return result;
}

var btnSub = document.getElementById("btnSub");
btnSub.onclick = function () {
    var disney = document.getElementsByName("disney")[0];
    var disVal = disney.options[disney.selectedIndex].value;
    var ret = validate(disVal);
    //ret is validate result
}