In WordPress you are not always in the PHP world and so you have to pass settings and data from the database to scripts sometimes. In many Plugins you can find solutions in loading the wp-load.php and therefore access to all features of WordPress. Long ago Otto (Samuel Wood) already referred to this fact and this articles shows solutions. Questions still there and still there are Plugins that load the wp-load.php precisely because of such problems.
A similar problem arises when the source of the scripts is not just written in the footer area of WordPress, but outsourced to a file and via wp_enqueue_script() included. Only then WordPress can manage, compromises and optimizes these scripts for delivery. Therefore I would like to show two examples, how to pass data from PHP to JS.
The first snippet uses the pass of values via JSON to get the values from the database with the current resources in PHP and the script stores directly in the header of the page the values as an object.
add_action( 'admin_enqueue_scripts', 'fb_print_scripts' );
function fb_print_scripts() {
global $current_screen;
if ( isset( $current_screen -> id ) && ! in_array( $current_screen -> id, array( 'post', 'page' ) ) )
return;
if ( is_plugin_active_for_network( plugin_basename( __FILE__ ) ) )
$options = get_site_option( 'my_options_id' );
else
$options = get_option( 'my_options_id' );
if ( ! $options )
return;
?>
<script type="text/javascript">
var my_json_object = <?php echo json_encode( $options ); ?>;
</script>
<?php
}
The above function gives the values from the database as a JSON object in the head of the backend, as the page was requested in the first step of the function. Via $current_screen it will be checked so it will be only delivered if you are on one of the defined pages (post, page).
The next step is common practice and best solution to include scripts in WordPress. Thereby I will include the JS file, which then has accesses to the JSON object.
add_action( 'admin_enqueue_scripts', 'fb_admin_enqueue_scripts' );
function fb_admin_enqueue_scripts( $where ) {
if ( ! in_array( $where, array( 'post.php', 'post-new.php', ) )
return;
$suffix = defined('SCRIPT_DEBUG') && SCRIPT_DEBUG ? '.dev' : '';
wp_enqueue_script(
self :: get_textdomain() . '_script',
plugins_url( '/js/my_script' . $suffix. '.js', __FILE__ ),
array( 'jquery', 'my_other_script' ),
'',
TRUE
);
}
The script accesses directly the object that is processed.
jQuery( document ).ready( function( $ ) {
if ( typeof my_json_object == 'undefined' )
return;
// debug in console of Browser
console.dir( my_json_object );
});
Another solution will be presented in the following post at this series.
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