Trigger Javascript on Gutenberg (Block Editor) Save

Not sure if there is a better way, but I am listening to subscribe rather than adding an event listener to the button:

wp.data.subscribe(function () {
  var isSavingPost = wp.data.select('core/editor').isSavingPost();
  var isAutosavingPost = wp.data.select('core/editor').isAutosavingPost();

  if (isSavingPost && !isAutosavingPost) {
    // Here goes your AJAX code ......

  }
})

Official docs of the Post Editor data: https://wordpress.org/gutenberg/handbook/designers-developers/developers/data/data-core-editor/