Support color ansi code sequences in custom help (#2251)

Readme.md

@@ -926,6 +926,7 @@ You can configure the Help behaviour by modifying data properties and methods us
 The data properties are:
 
 - `helpWidth`: specify the wrap width, useful for unit tests
+- `minWidthToWrap`: specify required width to allow wrapping (default 40)
 - `sortSubcommands`: sort the subcommands alphabetically
 - `sortOptions`: sort the options alphabetically
 - `showGlobalOptions`: show a section with the global options from the parent command(s)
@@ -941,6 +942,17 @@ program.configureHelp({
 });
 ```
 
+There are _style_ methods to add color to the help, like `styleTitle` and `styleOptionText`. There is built-in support for respecting
+environment variables for `NO_COLOR`, `FORCE_COLOR`, and `CLIFORCE_COLOR`.
+
+Example file: [color-help.mjs](./examples/color-help.mjs)
+
+Other help configuration examples:
+- [color-help-replacement.mjs](./examples/color-help-replacement.mjs)
+- [help-centered.mjs](./examples/help-centered.mjs)
+- [help-subcommands-usage.js](./examples/help-subcommands-usage.js)
+- [man-style-help.mjs](./examples/man-style-help.mjs)
+
 ## Custom event listeners
 
 You can execute custom actions by listening to command and option events.

examples/color-help-replacement.mjs

@@ -0,0 +1,113 @@
+import stripAnsi from 'strip-ansi';
+import wrapAnsi from 'wrap-ansi';
+import {
+  default as chalkStdOut,
+  chalkStderr as chalkStdErr,
+  supportsColor as supportsColorStdout,
+  supportsColorStderr,
+} from 'chalk';
+import { Command, Help } from 'commander';
+
+// Replace default color and wrapping support with Chalk packages as an example of
+// a deep replacement of format and style support.
+
+// This example requires chalk and wrap-ansi and strip-ansi, and won't run
+// from a clone of Commander repo without installing them first.
+//
+// For example using npm:
+//    npm install chalk wrap-ansi strip-ansi
+
+class MyHelp extends Help {
+  constructor() {
+    super();
+    this.chalk = chalkStdOut;
+  }
+
+  prepareContext(contextOptions) {
+    super.prepareContext(contextOptions);
+    if (contextOptions?.error) {
+      this.chalk = chalkStdErr;
+    }
+  }
+
+  displayWidth(str) {
+    return stripAnsi(str).length; // use imported package
+  }
+
+  boxWrap(str, width) {
+    return wrapAnsi(str, width, { hard: true }); // use imported package
+  }
+
+  styleTitle(str) {
+    return this.chalk.bold(str);
+  }
+  styleCommandText(str) {
+    return this.chalk.cyan(str);
+  }
+  styleCommandDescription(str) {
+    return this.chalk.magenta(str);
+  }
+  styleItemDescription(str) {
+    return this.chalk.italic(str);
+  }
+  styleOptionText(str) {
+    return this.chalk.green(str);
+  }
+  styleArgumentText(str) {
+    return this.chalk.yellow(str);
+  }
+  styleSubcommandText(str) {
+    return this.chalk.blue(str);
+  }
+}
+
+class MyCommand extends Command {
+  createCommand(name) {
+    return new MyCommand(name);
+  }
+  createHelp() {
+    return Object.assign(new MyHelp(), this.configureHelp());
+  }
+}
+
+const program = new MyCommand();
+
+// Override the color detection to use Chalk's detection.
+// Chalk overrides color support based on the `FORCE_COLOR` environment variable,
+// and looks for --color and --no-color command-line options.
+// See https://github.com/chalk/chalk?tab=readme-ov-file#supportscolor
+//
+// In general we want stripColor() to be consistent with displayWidth().
+program.configureOutput({
+  getOutHasColors: () => supportsColorStdout,
+  getErrHasColors: () => supportsColorStderr,
+  stripColor: (str) => stripAnsi(str),
+});
+
+program.description('program description '.repeat(10));
+program
+  .option('-s', 'short description')
+  .option('--long <number>', 'long description '.repeat(10))
+  .option('--color', 'force color output') // implemented by chalk
+  .option('--no-color', 'disable color output'); // implemented by chalk
+
+program.addHelpText('after', (context) => {
+  const chalk = context.error ? chalkStdErr : chalkStdOut;
+  return chalk.italic('\nThis is additional help text.');
+});
+
+program.command('esses').description('sssss '.repeat(33));
+
+program
+  .command('print')
+  .description('print files')
+  .argument('<files...>', 'files to queue for printing')
+  .option('--double-sided', 'print on both sides');
+
+program.parse();
+
+// Try the following (after installing the required packages):
+//    node color-help-replacement.mjs --help
+//    node color-help-replacement.mjs --no-color help
+//    FORCE_COLOR=0 node color-help-replacement.mjs help
+//    node color-help-replacement.mjs help print

examples/color-help.mjs

@@ -0,0 +1,41 @@
+import { styleText } from 'node:util'; // from node v20.12.0
+import { Command } from 'commander';
+
+// Customise colours and styles for help output.
+
+const program = new Command();
+
+program.configureHelp({
+  styleTitle: (str) => styleText('bold', str),
+  styleCommandText: (str) => styleText('cyan', str),
+  styleCommandDescription: (str) => styleText('magenta', str),
+  styleItemDescription: (str) => styleText('italic', str),
+  styleOptionText: (str) => styleText('green', str),
+  styleArgumentText: (str) => styleText('yellow', str),
+  styleSubcommandText: (str) => styleText('blue', str),
+});
+
+program.description('program description '.repeat(10));
+program
+  .option('-s', 'short description')
+  .option('--long <number>', 'long description '.repeat(10));
+
+program.addHelpText(
+  'after',
+  styleText('italic', '\nThis is additional help text.'),
+);
+
+program.command('esses').description('sssss '.repeat(33));
+
+program
+  .command('print')
+  .description('print files')
+  .argument('<files...>', 'files to queue for printing')
+  .option('--double-sided', 'print on both sides');
+
+program.parse();
+
+// Try the following:
+//    node color-help.mjs --help
+//    NO_COLOR=1 node color-help.mjs --help
+//    node color-help.mjs help print

examples/help-centered.mjs

@@ -0,0 +1,42 @@
+import { Command, Help } from 'commander';
+
+// Right-justify the terms in the help output.
+// Setup a subclass so we can do simple tweak of formatItem.
+
+class MyHelp extends Help {
+  formatItem(term, termWidth, description, helper) {
+    // Pre-pad the term at start instead of end.
+    const paddedTerm = term.padStart(
+      termWidth + term.length - helper.displayWidth(term),
+    );
+
+    return super.formatItem(paddedTerm, termWidth, description, helper);
+  }
+}
+
+class MyCommand extends Command {
+  createCommand(name) {
+    return new MyCommand(name);
+  }
+  createHelp() {
+    return Object.assign(new MyHelp(), this.configureHelp());
+  }
+}
+
+const program = new MyCommand();
+
+program.configureHelp({ MyCommand });
+
+program
+  .option('-s', 'short flag')
+  .option('-f, --flag', 'short and long flag')
+  .option('--long <number>', 'long flag');
+
+program.command('compile').alias('c').description('compile something');
+
+program.command('run', 'run something').command('print', 'print something');
+
+program.parse();
+
+// Try the following:
+//    node help-centered.mjs --help

examples/man-style-help.mjs

@@ -0,0 +1,41 @@
+import { Command } from 'commander';
+
+// Layout the help like a man page, with the description starting on the next line.
+
+function formatItem(term, termWidth, description, helper) {
+  const termIndent = 2;
+  const descIndent = 6;
+  const helpWidth = this.helpWidth || 80;
+
+  // No need to pad term as on its own line.
+  const lines = [' '.repeat(termIndent) + term];
+
+  if (description) {
+    const boxText = helper.boxWrap(description, helpWidth - 6);
+    const descIndentText = ' '.repeat(descIndent);
+    lines.push(
+      descIndentText + boxText.split('\n').join('\n' + descIndentText),
+    );
+  }
+
+  lines.push('');
+  return lines.join('\n');
+}
+
+const program = new Command();
+
+program.configureHelp({ formatItem });
+
+program
+  .option('-s', 'short flag')
+  .option('-f, --flag', 'short and long flag')
+  .option('--long <number>', 'l '.repeat(100));
+
+program
+  .command('sub1', 'sssss '.repeat(33))
+  .command('sub2', 'subcommand 2 description');
+
+program.parse();
+
+// Try the following:
+//    node man-style-help.mjs --help