Drupal 7 Module Development

The following code adds a system CSS file which is not preprocessed and is only
used for screen:
$path = drupal_get_path('module', 'hello_world');
$options = array(
'group' => CSS_SYSTEM,
'media' => 'screen',
'preprocess' => FALSE,
);
drupal_add_css($path . '/hello_world.css', $options);
Passing variables from PHP to JavaScript
Drupal provides a means of passing variables from PHP to JavaScript using
drupal_add_js(). Many applications want to pass configuration information
to JavaScript that runs on a page. This function is the means in Drupal to pass
that information easily.
Chapter 10
Drupal calls the variables passed from PHP to JavaScript settings. A simple example
of a setting that passes the text "Hello World!" from PHP to JavaScript would
look like:
drupal_add_js(array('helloWorld' => "Hello World!"), 'setting');
Variable names in the PHP portion of Drupal are in lowercase with
an underscore separating words. In JavaScript they should be in
lowerCamelCase. For more information see the coding standard at
http://drupal.org/coding-standards.
JavaScript can access this at Drupal.settings.helloWorld. For example the
following JavaScript would display the "Hello World" as a pop-up:
alert(Drupal.settings.helloWorld);
Settings are unlike other uses of drupal_add_js(). They are added to the page
in the header with a weight of JS_LIBRARY. There are no other options besides
specifying that it is a setting, as shown in the following example:
drupal_add_js(array('hello_world' => "Hello World!"), 'setting');
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