JSFiddle - React, Tailwind, and code Playground

by kurotanshi

HTML

<select id="a1">
    <option value="a01">a01</option>
    <option value="a02">a02</option>
    <option value="a03">a03</option>
</select>
<select id="a2">
    <option value="">請選擇</option>
    <option value="b01">b01</option>
    <option value="b02">b02</option>
    <option value="b03">b03</option>
</select>
<select id="a3">
    <option value="">請選擇</option>
    <option value="c01">c01</option>
    <option value="c02">c02</option>
    <option value="c03">c03</option>
</select>
<select id="a4">
    <option value="">請選擇</option>
    <option value="d01">d01</option>
    <option value="d02">d02</option>
    <option value="d03">d03</option>
</select>
<br/><br/>
<button>Go</button>

JavaScript

$("button").click(function() {
    var val = 0;
    $.each($("select:not(:first)"), function(index, value) {
        if ($(this).val() == '') {
            val = index;
            return false;
        }
        else {
            val = index + 1;
        }
    });
    alert($("select:eq(" + val + ")").val());
});