JSFiddle - React, Tailwind, and code Playground

HTML

<select name="name1" class="add_purch_item">
    <option value="" selected="selected">-----</option>
    <option value="1">value1</option>
    <option value="2">value2</option>
</select>
<select name="name2" class="add_purch_item">
    <option value="" selected="selected">-----</option>
    <option value="1">value1</option>
    <option value="2">value2</option>
</select>
<button id="submit">Check</button>

JavaScript

$(document).on("click", '#submit', function () {
    var selected = [];
    $('.add_purch_item').each(function () {
        var val = $(this).val();
        if (val) {
            selected.push(val);
        }
    });
    alert(selected);
});