JSFiddle - React, Tailwind, and code Playground

HTML

<input type="checkbox" value="1"> 1 <br/>
<input type="checkbox" value="2"> 2 <br/>
<input type="checkbox" value="3"> 3 <br/>

<div id="output"></div>

JavaScript

$('input').on('change', function() {
    var values = $('input:checked').map(function() {
        return this.value;
    }).get();
    
    $('#output').append(values.toString()).append('<br/>');
});