name : no-repeated-options.js 'use strict'; // This is an example of using tokens to add a custom behaviour. // // Throw an error if an option is used more than once. // 1. const { parseArgs } = require('node:util'); // from node // 2. const { parseArgs } = require('@pkgjs/parseargs'); // from package const { parseArgs } = require('..'); // in repo const options = { ding: { type: 'boolean', short: 'd' }, beep: { type: 'boolean', short: 'b' } }; const { values, tokens } = parseArgs({ options, tokens: true }); const seenBefore = new Set(); tokens.forEach((token) => { if (token.kind !== 'option') return; if (seenBefore.has(token.name)) { throw new Error(`option '${token.name}' used multiple times`); } seenBefore.add(token.name); }); console.log(values); // Try the following: // node no-repeated-options --ding --beep // node no-repeated-options --beep -b // node no-repeated-options -ddd