<div class="p-2">
<form onsubmit="return handleData()" method="post" action="https://postman-echo.com/post">
<p>Select all the scripting languages you know:</p>
<div>
<input type="checkbox" name="langs" id="langs_javascript" value="JavaScript" checked> <label for="langs_javascript">JavaScript</label>
</div>
<div>
<input type="checkbox" name="langs" id="langs_perl" value="Perl"> <label for="langs_perl">Perl</label>
</div>
<div>
<input type="checkbox" name="langs" id="langs_php" value="PHP" checked> <label for="langs_php">PHP</label>
</div>
<div>
<input type="checkbox" name="langs" id="langs_ruby" value="Ruby"> <label for="langs_ruby">Ruby</label>
</div>
<div>
<input type="submit" name="submit" value="Submit"/>
</div>
</form>
</div>
function handleData()
{
    var form_data = new FormData(document.querySelector("form"));
    console.log("form data: ");
    for(var pair of form_data.entries()) 
    {
        console.log(pair[0]+ ' : '+ pair[1]);
    }
    return true;
}

External CSS

  1. https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.3/css/bootstrap.min.css

External JavaScript

This Pen doesn't use any external JavaScript resources.