wp_theme_has_theme_json()

wp_theme_has_theme_json(): bool

function wp_theme_has_theme_json() {
	static $theme_has_support = array();

	$stylesheet = get_stylesheet();

	if (
		isset( $theme_has_support[ $stylesheet ] ) &&
		/*
		 * Ignore static cache when the development mode is set to 'theme', to avoid interfering with
		 * the theme developer's workflow.
		 */
		! wp_is_development_mode( 'theme' )
	) {
		return $theme_has_support[ $stylesheet ];
	}

	$stylesheet_directory = get_stylesheet_directory();
	$template_directory   = get_template_directory();

	// This is the same as get_theme_file_path(), which isn't available in load-styles.php context
	if ( $stylesheet_directory !== $template_directory && file_exists( $stylesheet_directory . '/theme.json' ) ) {
		$path = $stylesheet_directory . '/theme.json';
	} else {
		$path = $template_directory . '/theme.json';
	}

	/** This filter is documented in wp-includes/link-template.php */
	$path = apply_filters( 'theme_file_path', $path, 'theme.json' );

	$theme_has_support[ $stylesheet ] = file_exists( $path );

	return $theme_has_support[ $stylesheet ];
}