wp_html_custom_data_attribute_name( string $js_dataset_name ): string|null

4039function wp_html_custom_data_attribute_name( string $js_dataset_name ): ?string {4040	$end = strlen( $js_dataset_name );4041	if ( 0 === $end ) {4042		return 'data-';4043	}4044 4045	/*4046	 * If it contains characters which would end the attribute name parsing then4047	 * something it’s not possible to represent this in HTML.4048	 */4049	if ( strcspn( $js_dataset_name, "=/> \t\f\r\n" ) !== $end ) {4050		return null;4051	}4052 4053	$html_name = 'data-';4054	$at        = 0;4055	$was_at    = $at;4056 4057	while ( $at < $end ) {4058		$next_upper_after = strcspn( $js_dataset_name, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', $at );4059		$next_upper_at    = $at + $next_upper_after;4060		if ( $next_upper_at >= $end ) {4061			break;4062		}4063 4064		$prefix     = substr( $js_dataset_name, $was_at, $next_upper_at - $was_at );4065		$html_name .= strtolower( $prefix );4066		$html_name .= '-' . strtolower( $js_dataset_name[ $next_upper_at ] );4067		$at         = $next_upper_at + 1;4068		$was_at     = $at;4069	}4070 4071	if ( $was_at < $end ) {4072		$html_name .= strtolower( substr( $js_dataset_name, $was_at ) );4073	}4074 4075	return $html_name;4076}