JSFiddle - React, Tailwind, and code Playground

by Ben Bankes

HTML

<form action="upload.php" method="POST" enctype="multipart/form-data">
     <input type="file" name="imageURL[]" id="imageURL" />

     <input type="submit" value="submit" name="submit" id="yourUniqueId" />
</form>

JavaScript

var submitButton = document.getElementById('yourUniqueId');
submitButton.setAttribute('style', 'display:none;');

document.getElementById('imageURL').onchange = function() {
    submitButton.removeAttribute('style');
};