WordPress at a glance
action is not described

customize_preview_init action-hook . WP 3.4.0

Fires once the Customizer preview has initialized and JavaScript settings have been printed.

Usage

add_action( 'customize_preview_init', 'action_function_name_6346' );
function action_function_name_6346( $this ){
	// action...
}
$this(WP_Customize_Manager)
WP_Customize_Manager instance.

Where the hook is called

WP_Customize_Manager::customize_preview_init()
wp-includes/class-wp-customize-manager.php 1872
do_action( 'customize_preview_init', $this );

Where the hook is used (in WP core)

wp-includes/customize/class-wp-customize-selective-refresh.php 67
add_action( 'customize_preview_init', array( $this, 'init_preview' ) );
wp-includes/class-wp-customize-widgets.php 119
add_action( 'customize_preview_init', array( $this, 'customize_preview_init' ) );
wp-includes/class-wp-customize-widgets.php 128
add_action( 'customize_preview_init', array( $this, 'selective_refresh_init' ) );
wp-includes/class-wp-customize-nav-menus.php 66
add_action( 'customize_preview_init', array( $this, 'customize_preview_init' ) );
wp-includes/class-wp-customize-nav-menus.php 67
add_action( 'customize_preview_init', array( $this, 'make_auto_draft_status_previewable' ) );