WP_Customize_Widgets::get_post_value( string $name, mixed $default = null )

Source

File: wp-includes/class-wp-customize-widgets.php

protected function get_post_value( $name, $default = null ) {
		if ( ! isset( $_POST[ $name ] ) ) {
			return $default;
		}

		return wp_unslash( $_POST[ $name ] );
	}