Commander.js

Commander 15 is ESM only. This is expected to be seamless for ESM consumers, but some CommonJS consumers may hit issues with tooling requiring configuration for ESM-only dependencies. See Migration Tips below.

The release of Commander 15 moves Commander 14 into maintenance. Commander 14 will get security updates for 12 months (to May 2027). For more info see Release Policy.

Added

• show excess command-arguments in error message (#2384)

Fixed

• Breaking: only lone --no-* option sets default option value to true, default not implicitly set when define both positive and negative option in either order (#2405)
• update example to use compatible character for MINGW64 (#2475)

Changed

• Breaking: migrated Commander implementation from CommonJS to ESM (#2464)
• Breaking: Commander 15 requires Node.js v22.12.0 or higher (for require(esm)).
• dev: switch tests from Jest to node:test test runner (#2463)

Deleted

• Breaking: removed deprecated export of commander/esm.mjs (#2464)

Migration Tips

Commander 15 is ESM only, but this does not mean you need to migrate to ESM to use it. Importing ESM from CommonJS is supported by Node.js, and Bun, and Deno. Hopefully it Just Works for you! However, you may be using a different runtime or some other part of your setup that may not yet natively support importing ESM from CommonJS, such as your testing framework or bundler.

If you have problems using Commander 15 in your environment, one option is stay on Commander 14 for now. Commander 14 will get security updates until May 2027 and things will hopefully improve for your setup in the meantime.

Commander 15 is ESM only. This is expected to be seamless for ESM consumers, but some CommonJS consumers may hit issues with tooling requiring configuration for ESM-only dependencies. See Migration Tips below.

The release of Commander 15 in May 2026 will move Commander 14 into maintenance. Commander 14 will get security updates for 12 months (to May 2027). For more info see Release Policy.

Added

• show excess command-arguments in error message (#2384)

Fixed

• Breaking: only lone --no-* option sets default option value to true, default not implicitly set when define both positive and negative option in either order (#2405)
• update example to use compatible character for MINGW64 (#2475)

Changed

• Breaking: migrated Commander implementation from CommonJS to ESM (#2464)
• Breaking: Commander 15 requires Node.js v22.12.0 or higher (for require(esm)).
• dev: switch tests from Jest to node:test test runner (#2463)

Deleted

• Breaking: removed deprecated export of commander/esm.mjs (#2464)

Migration Tips

Commander 15 is ESM only, but this does not mean you need to migrate to ESM to use it. Importing ESM from CommonJS is supported by Node.js, and Bun, and Deno. Hopefully it Just Works for you! However, you may be using a different runtime or some other part of your setup that may not yet natively support importing ESM from CommonJS, such as your testing framework or bundler.

If you have problems using Commander 15 in your environment, one option is stay on Commander 14 for now. Commander 14 will get security updates until May 2027 and things will hopefully improve for your setup in the meantime.

To allow require(esm) from CommonJS you may be able to make small changes to your current setup. Some examples for Jest are included in examples/using-esm-from-commonjs. (Commander was using Jest, so we have a special interest.)

Added

• Release Policy document (#2462)

Changes

• old major versions now supported for 12 months instead of just previous major version, to give predictable end-of-life date (#2462)
• clarify typing for deprecated callback parameter to .outputHelp() (#2427)
• simple readability improvements to README (#2465)

Changed

• improve negative number auto-detection test (#2428)
• update (dev) dependencies

Fixed

• broken markdown link in README (#2369)

Changed

• improve code readability by using optional chaining (#2394)
• use more idiomatic code with object spread instead of Object.assign() (#2395)
• improve code readability using string.endsWith() instead of string.slice() (#2396)
• refactor .parseOptions() to process args array in-place (#2409)
• change private variadic support routines from ._concatValue() to ._collectValue() (change code from array.concat() to array.push()) (#2410)
• update (dev) dependencies

Added

• support for groups of options and commands in the help using low-level .helpGroup() on Option and Command, and higher -level .optionsGroup() and .commandsGroup() which can be used in chaining way to specify group title for following option s/commands (#2328)
• support for unescaped negative numbers as option-arguments and command-arguments (#2339)
• TypeScript: add parseArg property to Argument class (#2359)

Fixed

• remove bogus leading space in help when option has default value but not a description (#2348)
• .configureOutput() now makes copy of settings instead of modifying in-place, fixing side-effects (#2350)

Changed

• Breaking: Commander 14 requires Node.js v20 or higher
• internal refactor of Help class adding .formatItemList() and .groupItems() methods (#2328)

Added

• support a pair of long option flags to allow a memorable shortened flag, like .option('--ws, --workspace') (#2312)

Added

• support multiple calls to .parse() with default settings (#2299)
• add .saveStateBeforeParse() and .restoreStateBeforeParse() for use by subclasses (#2299)
• style routines like styleTitle() to add color to help using .configureHelp() or Help subclass (#2251)
• color related support in .configureOutput() for getOutHasColors(), getErrHasColors(), and stripColor() (#2251)
• Help property for minWidthToWrap (#2251)
• Help methods for displayWidth(), boxWrap(), preformatted() et al (#2251)

Changed

• Breaking: excess command-arguments cause an error by default, see migration tips (#2223)
• Breaking: throw during Option construction for unsupported option flags, like multiple characters after single - (#2270)
• Breaking: throw on multiple calls to .parse() if storeOptionsAsProperties: true (#2299)
• TypeScript: include implicit this in parameters for action handler callback (#2197)

Deleted

• Breaking: Help.wrap() refactored into formatItem() and boxWrap() (#2251)

Migration Tips

Excess command-arguments

It is now an error for the user to specify more command-arguments than are expected. (allowExcessArguments is now false by default.)

Old code:

program.option('-p, --port <number>', 'port number');
program.action((options) => {
  console.log(program.args);
});

Now shows an error:

$ node example.js a b c
error: too many arguments. Expected 0 arguments but got 3.

You can declare the expected arguments. The help will then be more accurate too. Note that declaring new arguments will change what is passed to the action handler.

program.option('-p, --port <number>', 'port number');
program.argument('[args...]', 'remote command and arguments'); // expecting zero or more arguments
program.action((args, options) => {
  console.log(args);
});

Or you could suppress the error, useful for minimising changes in legacy code.

program.option('-p, --port', 'port number');
program.allowExcessArguments();
program.action((options) => {
  console.log(program.args);
});

Added

• style routines like styleTitle() to add color to help using .configureHelp() or Help subclass (#2251)
• color related support in .configureOutput() for getOutHasColors(), getErrHasColors(), and stripColor() (#2251)
• Help property for minWidthToWrap (#2251)
• Help methods for displayWidth(), boxWrap(), preformatted() et al (#2251)

Changed

• Breaking: excess command-arguments cause an error by default, see migration tips (#2223)
• Breaking: throw during Option construction for unsupported option flags, like multiple characters after single - (#2270)
• TypeScript: include implicit this in parameters for action handler callback (#2197)

Deleted

• Breaking: Help.wrap() refactored into formatItem() and boxWrap() (#2251)

Migration Tips

Excess command-arguments

It is now an error for the user to specify more command-arguments than are expected. (allowExcessArguments is now false by default.)

Old code:

program.option('-p, --port <number>', 'port number');
program.action((options) => {
  console.log(program.args);
});

Now shows an error:

$ node example.js a b c
error: too many arguments. Expected 0 arguments but got 3.

You can declare the expected arguments. The help will then be more accurate too. Note that declaring new arguments will change what is passed to the action handler.

program.option('-p, --port <number>', 'port number');
program.argument('[args...]', 'remote command and arguments'); // expecting zero or more arguments
program.action((args, options) => {
  console.log(args);
});

Or you could suppress the error, useful for minimising changes in legacy code.

program.option('-p, --port', 'port number');
program.allowExcessArguments();
program.action((options) => {
  console.log(program.args);
});

Added

• auto-detect special node flags node --eval and node --print when call .parse() with no arguments (#2164)

Changed

• prefix require of Node.js core modules with node: (#2170)
• format source files with Prettier (#2180)
• switch from StandardJS to directly calling ESLint for linting (#2153)
• extend security support for previous major version of Commander (#2150)

Removed

• removed unimplemented Option.fullDescription from TypeScript definition (#2191)