Another powerful thing we can do (and something we often need to do) is pass values from our PHP code to the JavaScript layer. In custom PHP applications, this can get messy, but Drupal has a robust API that transforms PHP arrays into JavaScript objects. These can be found inside the settings object passed to the behavior's attach() function.
Again, the easiest way to understand this is through an example. So let's say we want to print an extra message after the salutation if we are in the afternoon. Of course, we can use JavaScript to determine that as well, but so far it has been the responsibility of our PHP code, so let's keep it that way. So then we need a way to tell our JavaScript that it is afternoon, and we can do ...
