JSFiddle - React, Tailwind, and code Playground

HTML

<form id='form' action='javascript: void(0)' method='post'>
    <input type='text' />
    <input type='submit' />
</form>

JavaScript

var sent = false;
$('#form').submit(function(e) {
    e.preventDefault();
    if (!sent) {
        sent = true;
        alert('sent');
    }
    else alert('already sent');
});