WP_Customize_Manager::customize_preview_settings()

	public function customize_preview_settings() {
		$post_values = $this->unsanitized_post_values( array( 'exclude_changeset' => true ) );
		$setting_validities = $this->validate_setting_values( $post_values );
		$exported_setting_validities = array_map( array( $this, 'prepare_setting_validity_for_js' ), $setting_validities );

		// Note that the REQUEST_URI is not passed into home_url() since this breaks subdirectory installations.
		$self_url = empty( $_SERVER['REQUEST_URI'] ) ? home_url( '/' ) : esc_url_raw( wp_unslash( $_SERVER['REQUEST_URI'] ) );
		$state_query_params = array(
			'customize_theme',
			'customize_changeset_uuid',
			'customize_messenger_channel',
		);
		$self_url = remove_query_arg( $state_query_params, $self_url );

		$allowed_urls = $this->get_allowed_urls();
		$allowed_hosts = array();
		foreach ( $allowed_urls as $allowed_url ) {
			$parsed = wp_parse_url( $allowed_url );
			if ( empty( $parsed['host'] ) ) {
				continue;
			}
			$host = $parsed['host'];
			if ( ! empty( $parsed['port'] ) ) {
				$host .= ':' . $parsed['port'];
			}
			$allowed_hosts[] = $host;
		}

		$switched_locale = switch_to_locale( get_user_locale() );
		$l10n = array(
			'shiftClickToEdit' => __( 'Shift-click to edit this element.' ),
			'linkUnpreviewable' => __( 'This link is not live-previewable.' ),
			'formUnpreviewable' => __( 'This form is not live-previewable.' ),
		);
		if ( $switched_locale ) {
			restore_previous_locale();
		}

		$settings = array(
			'changeset' => array(
				'uuid' => $this->changeset_uuid(),
				'autosaved' => $this->autosaved(),
			),
			'timeouts' => array(
				'selectiveRefresh' => 250,
				'keepAliveSend' => 1000,
			),
			'theme' => array(
				'stylesheet' => $this->get_stylesheet(),
				'active'     => $this->is_theme_active(),
			),
			'url' => array(
				'self' => $self_url,
				'allowed' => array_map( 'esc_url_raw', $this->get_allowed_urls() ),
				'allowedHosts' => array_unique( $allowed_hosts ),
				'isCrossDomain' => $this->is_cross_domain(),
			),
			'channel' => $this->messenger_channel,
			'activePanels' => array(),
			'activeSections' => array(),
			'activeControls' => array(),
			'settingValidities' => $exported_setting_validities,
			'nonce' => current_user_can( 'customize' ) ? $this->get_nonces() : array(),
			'l10n' => $l10n,
			'_dirty' => array_keys( $post_values ),
		);

		foreach ( $this->panels as $panel_id => $panel ) {
			if ( $panel->check_capabilities() ) {
				$settings['activePanels'][ $panel_id ] = $panel->active();
				foreach ( $panel->sections as $section_id => $section ) {
					if ( $section->check_capabilities() ) {
						$settings['activeSections'][ $section_id ] = $section->active();
					}
				}
			}
		}
		foreach ( $this->sections as $id => $section ) {
			if ( $section->check_capabilities() ) {
				$settings['activeSections'][ $id ] = $section->active();
			}
		}
		foreach ( $this->controls as $id => $control ) {
			if ( $control->check_capabilities() ) {
				$settings['activeControls'][ $id ] = $control->active();
			}
		}

		?>
		<script type="text/javascript">
			var _wpCustomizeSettings = <?php echo wp_json_encode( $settings ); ?>;
			_wpCustomizeSettings.values = {};
			(function( v ) {
				<?php
				/*
				 * Serialize settings separately from the initial _wpCustomizeSettings
				 * serialization in order to avoid a peak memory usage spike.
				 * @todo We may not even need to export the values at all since the pane syncs them anyway.
				 */
				foreach ( $this->settings as $id => $setting ) {
					if ( $setting->check_capabilities() ) {
						printf(
							"v[%s] = %s;\n",
							wp_json_encode( $id ),
							wp_json_encode( $setting->js_value() )
						);
					}
				}
				?>
			})( _wpCustomizeSettings.values );
		</script>
		<?php
	}