Node.jsでコマンドラインツールを作る時にオプション引数をいい感じに扱いたい

結論

command-line-args と command-line-usage を使うといい感じになる

オプション引数の説明を表示する

src/index.js

const commandLineUsage = require("command-line-usage");
const usage = commandLineUsage([
  { header: "command line tool", content: "description" },
  {
    header: "Options",
    optionList: [
      { name: "str", description: "description of str" },
      { name: "multi", description: "ex: --multi foo --multi bar" },
      { name: "int", description: "default: 123" },
      { name: "bool", alias: "b", type: Boolean, description: "ex: -b" },
    ],
  },
]);
console.log(usage);

出力

$ node src/index.js

command line tool

  description

Options

  --str string     description of str
  --multi string   ex: --multi foo --multi bar
  --int string     default: 123
  -b, --bool       ex: -b

オプション引数の値を取得する

src/index.js

const commandLineArgs = require("command-line-args");
const args = commandLineArgs([
  { name: "str", type: String },
  { name: "multi", multiple: true, type: String },
  { name: "bool", alias: "b", type: Boolean },
  { name: "int", type: Number, defaultValue: 123 },
  { name: "def", defaultOption: true },
]);
console.log(args);

出力

$ node src/index.js --str hoge --multi foo --multi bar -b foobar

{
  int: 123,
  str: 'hoge',
  multi: [ 'foo', 'bar' ],
  bool: true,
  def: 'foobar'
}