<form enctype="multipart/form-data" action="/photo" method="post">
<input type="hidden" name="section_id" value="234" />
<input type="file" multiple="multiple" id="section_photos" name="section_photos[]" accept=".jpg, .png, .gif" />
</form>

document.getElementById('input')
  .addEventListener('change', function(e){
  console.log(e);
});