wp_js_dataset_name( string $html_attribute_name ): string|null

4074function wp_js_dataset_name( string $html_attribute_name ): ?string {4075	if ( 0 !== substr_compare( $html_attribute_name, 'data-', 0, 5, true ) ) {4076		return null;4077	}4078 4079	$end = strlen( $html_attribute_name );4080 4081	/*4082	 * If it contains characters which would end the attribute name parsing then4083	 * something else is wrong and this contains more than just an attribute name.4084	 */4085	if ( ( $end - 5 ) !== strcspn( $html_attribute_name, "=/> \t\f\r\n", 5 ) ) {4086		return null;4087	}4088 4089	/**4090	 * > For each name in list, for each U+002D HYPHEN-MINUS character (-)4091	 * > in the name that is followed by an ASCII lower alpha, remove the4092	 * > U+002D HYPHEN-MINUS character (-) and replace the character that4093	 * > followed it by the same character converted to ASCII uppercase.4094	 *4095	 * @see https://html.spec.whatwg.org/#concept-domstringmap-pairs4096	 */4097	$custom_name = '';4098	$at          = 5;4099	$was_at      = $at;4100 4101	while ( $at < $end ) {4102		$next_dash_at = strpos( $html_attribute_name, '-', $at );4103		if ( false === $next_dash_at || $next_dash_at === $end - 1 ) {4104			break;4105		}4106 4107		// Transform `-a` to `A`, for example.4108		$c = $html_attribute_name[ $next_dash_at + 1 ];4109		if ( ( $c >= 'A' && $c <= 'Z' ) || ( $c >= 'a' && $c <= 'z' ) ) {4110			$prefix       = substr( $html_attribute_name, $was_at, $next_dash_at - $was_at );4111			$custom_name .= strtolower( $prefix );4112			$custom_name .= strtoupper( $c );4113			$at           = $next_dash_at + 2;4114			$was_at       = $at;4115			continue;4116		}4117 4118		$at = $next_dash_at + 1;4119	}4120 4121	// If nothing has been added it means there are no dash-letter pairs; return the name as-is.4122	return '' === $custom_name4123		? strtolower( substr( $html_attribute_name, 5 ) )4124		: ( $custom_name . strtolower( substr( $html_attribute_name, $was_at ) ) );4125}