All notable changes to this project will be documented in this file.
The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html). (Format adopted after v3.0.0.)
<!-- markdownlint-disable MD024 -->
## [5.1.0] (2020-04-25)
### Added
- support for multiple command aliases, the first of which is shown in the auto-generated help ([#531], [#1236])
- configuration support in `addCommand()` for `hidden` and `isDefault` ([#1232])
### Fixed
- omit masked help flags from the displayed help ([#645], [#1247])
- remove old short help flag when change help flags using `helpOption` ([#1248])
### Changed
- remove use of `arguments` to improve auto-generated help in editors ([#1235])
- rename `.command()` configuration `noHelp` to `hidden` (but not remove old support) ([#1232])
- improvements to documentation
- update dependencies
- update tested versions of node
- eliminate lint errors in TypeScript ([#1208])
## [5.0.0] (2020-03-14)
### Added
* support for nested commands with action-handlers ([#1] [#764] [#1149])
*`.addCommand()` for adding a separately configured command ([#764] [#1149])
* allow a non-executable to be set as the default command ([#742] [#1149])
* implicit help command when there are subcommands (previously only if executables) ([#1149])
* customise implicit help command with `.addHelpCommand()` ([#1149])
* display error message for unknown subcommand, by default ([#432] [#1088] [#1149])
* display help for missing subcommand, by default ([#1088] [#1149])
* combined short options as single argument may include boolean flags and value flag and value (e.g. `-a -b -p 80` can be written as `-abp80`) ([#1145])
*`.parseOption()` includes short flag and long flag expansions ([#1145])
*`.helpInformation()` returns help text as a string, previously a private routine ([#1169])
*`.parse()` implicitly uses `process.argv` if arguments not specified ([#1172])
* optionally specify where `.parse()` arguments "from", if not following node conventions ([#512] [#1172])
* suggest help option along with unknown command error ([#1179])
* TypeScript definition for `commands` property of `Command` ([#1184])
* export `program` property ([#1195])
*`createCommand` factory method to simplify subclassing ([#1191])
### Fixed
* preserve argument order in subcommands ([#508] [#962] [#1138])
* do not emit `command:*` for executable subcommands ([#809] [#1149])
* action handler called whether or not there are non-option arguments ([#1062] [#1149])
* combining option short flag and value in single argument now works for subcommands ([#1145])
* only add implicit help command when it will not conflict with other uses of argument ([#1153] [#1149])
* implicit help command works with command aliases ([#948] [#1149])
* options are validated whether or not there is an action handler ([#1149])
### Changed
* *Breaking* `.args` contains command arguments with just recognised options removed ([#1032] [#1138])
* *Breaking* display error if required argument for command is missing ([#995] [#1149])
* tighten TypeScript definition of custom option processing function passed to `.option()` ([#1119])
* unknown options included in arguments passed to command action handler
* unknown options included in `.args`
* only recognised option short flags and long flags are expanded (e.g. `-ab` or `--foo=bar`) ([#1145])
* *Breaking* `.parseOptions()` ([#1138])
*`args` in returned result renamed `operands` and does not include anything after first unknown option
*`unknown` in returned result has arguments after first unknown option including operands, not just options and values
* *Breaking* `.on('command:*', callback)` and other command events passed (changed) results from `.parseOptions`, i.e. operands and unknown ([#1138])
* refactor Option from prototype to class ([#1133])
* refactor Command from prototype to class ([#1159])
* changes to error handling ([#1165])
* throw for author error, not just display message
* preflight for variadic error
* add tips to missing subcommand executable
* TypeScript fluent return types changed to be more subclass friendly, return `this` rather than `Command` ([#1180])
*`.parseAsync` returns `Promise<this>` to be consistent with `.parse()` ([#1180])
* update dependencies
### Removed
* removed EventEmitter from TypeScript definition for Command, eliminating implicit peer dependency on `@types/node` ([#1146])
* removed private function `normalize` (the functionality has been integrated into `parseOptions`) ([#1145])
*`parseExpectedArgs` is now private ([#1149])
### Migration Tips
If you use `.on('command:*')` or more complicated tests to detect an unrecognised subcommand, you may be able to delete the code and rely on the default behaviour.
If you use `program.args` or more complicated tests to detect a missing subcommand, you may be able to delete the code and rely on the default behaviour.
If you use `.command('*')` to add a default command, you may be be able to switch to `isDefault:true` with a named command.
## [5.0.0-4] (2020-03-03)
(Released in 5.0.0)
## [5.0.0-3] (2020-02-20)
(Released in 5.0.0)
## [5.0.0-2] (2020-02-10)
(Released in 5.0.0)
## [5.0.0-1] (2020-02-08)
(Released in 5.0.0)
## [5.0.0-0] (2020-02-02)
(Released in 5.0.0)
## [4.1.1] (2020-02-02)
### Fixed
* TypeScript definition for `.action()` should include Promise for async ([#1157])
## [4.1.0] (2020-01-06)
### Added
* two routines to change how option values are handled, and eliminate name clashes with command properties ([#933] [#1102])
* see storeOptionsAsProperties and passCommandToAction in README
*`.parseAsync` to use instead of `.parse` if supply async action handlers ([#806] [#1118])
### Fixed
* Remove trailing blanks from wrapped help text ([#1096])
### Changed
* update dependencies
* extend security coverage for Commander 2.x to 2020-02-03
* improvements to README
* improvements to TypeScript definition documentation
* move old versions out of main CHANGELOG
* removed explicit use of `ts-node` in tests
## [4.0.1] (2019-11-12)
### Fixed
* display help when requested, even if there are missing required options ([#1091])
## [4.0.0] (2019-11-02)
### Added
* automatically wrap and indent help descriptions for options and commands ([#1051])
