I'm trying to upload an image with PubNub API in Ruby on Rails.

This is the input to upload the image and a button to call the function testf()

= file_field_tag "image", accept: 'image/jpeg, image/png', id: 'image_submit', name: "input[file]"
button onclick="testf()" test 

javascript:

const input = document.querySelector('#image_submit');
  
function testf(){
  const [file] = input.files;
  pubnub.sendFile({
    channel: 'my_channel',
    file: file,
  })
}