Formulário

form.html

 <form id="upload_form" enctype="multipart/form-data" method="post">
    <input type="file" name="file1" id="file1"><br>
    <progress id="progressBar" value="0" max="100" style="width:300px;"></progress>
    <h3 id="status"></h3>
    <p id="loaded_n_total"></p>
    <hr />
    <button type="submit">Enviar arquivo</button>
</form>