prevent caching during tinymce custom button development

Question

I'm following this turial on how to add a custom button to TinyMCE editor in WordPress. Trying to edit author's JS to include my functionality, yet it seems to have gotten cached. Article author has a hack for it (code snippet below), and it did work for the first time (the button is in the toolbar now), although it doesn't work for subsequent refreshes.

// "This will intercept the version check and increment the current version number by 3.
// It's the quick and dirty way to do it without messing with the settings directly..."
function my_refresh_mce($ver) {
  $ver += 3;
  return $ver;
}

add_filter( 'tiny_mce_version', 'my_refresh_mce');

What can I do to disable the caching?

Latest fresh WordPress localhost install, no plugins activated.

Answer 1

Turns out the 'no plugins activated' was not enough. Once I did a completely fresh install (without W3 Total Cache plugin), the issue disappeared.