How to communicate from the backend to javascript in Drupal 7.

drinks.js

(function($) {
  Drupal.behaviors.drinks = {
    attach: function(context, settings) {
      var drinkType = settings.drinks.page_type;
      alert('This page is of type: ' + drinkType);
    }
  }
})(jQuery);

drinks.module

<?php
// assume you have access to a $node object.

switch($node->type) {
  case 'beer':
    $type = 'beer';
    break;
  
  case 'soda':
    $type = 'soda';
    break;
    
  default:
    $type = 'water';
}

drupal_add_js(array('drinks' => array('page_type' => $type)), 'setting');