JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://raw.github.com/macek/jquery-serialize-object/master/jquery.serialize-object.js"></script>
<form>
    <!-- the wrong way: name="foo" -->
    <select multiple="multiple" name="foo">
        <option value="1" selected="selected">1</option>
        <option value="2" selected="selected">2</option>
        <option value="3" selected="selected">3</option>
        <option value="4">4</option>
        <option value="5">5</option>
    </select>
    
    <!-- the right way: name="bar[]" -->
    <select multiple="multiple" name="bar[]">
        <option value="1" selected="selected">1</option>
        <option value="2" selected="selected">2</option>
        <option value="3" selected="selected">3</option>
        <option value="4">4</option>
        <option value="5">5</option>
    </select>
</form>

JavaScript

$(function(){
    console.log($('form').serializeObject());
});