WordPress at a glance
function is not described

_wp_customize_loader_settings() WP 3.4.0

Adds settings for the customize-loader script.

No Hooks.

Return

Nothing (null).

Usage

_wp_customize_loader_settings();

Code of wp customize loader settings: wp-includes/theme.php VER 5.1.1

<?php
function _wp_customize_loader_settings() {
	$admin_origin = parse_url( admin_url() );
	$home_origin  = parse_url( home_url() );
	$cross_domain = ( strtolower( $admin_origin['host'] ) != strtolower( $home_origin['host'] ) );

	$browser = array(
		'mobile' => wp_is_mobile(),
		'ios'    => wp_is_mobile() && preg_match( '/iPad|iPod|iPhone/', $_SERVER['HTTP_USER_AGENT'] ),
	);

	$settings = array(
		'url'           => esc_url( admin_url( 'customize.php' ) ),
		'isCrossDomain' => $cross_domain,
		'browser'       => $browser,
		'l10n'          => array(
			'saveAlert'       => __( 'The changes you made will be lost if you navigate away from this page.' ),
			'mainIframeTitle' => __( 'Customizer' ),
		),
	);

	$script = 'var _wpCustomizeLoaderSettings = ' . wp_json_encode( $settings ) . ';';

	$wp_scripts = wp_scripts();
	$data       = $wp_scripts->get_data( 'customize-loader', 'data' );
	if ( $data ) {
		$script = "$data\n$script";
	}

	$wp_scripts->add_data( 'customize-loader', 'data', $script );
}