fastfetch.js

const str = `    -h, --help <?command>:      Show this message, or help for a specific command
    -v, --version:              Show the version of fastfetch
    --list-config-paths:        List search paths of config files
    --list-data-paths:          List search paths of presets and logos
    --list-logos:               List available logos
    --list-modules:             List available modules
    --list-presets:             List presets fastfetch knows about; they can be loaded with --load-config (+)
    --list-features:            List the supported features fastfetch was compiled with (mainly for development)
    --print-logos:              Print available logos
    --print-config-system:      Print the default system config
    --print-config-user:        Print the default user config
    --print-structure:          Print the default structure`;

const flags = str
  .trim()
  .split("\n")
  .map((x) => {
    x = x.trim();
    let i = x.indexOf(":");
    return { left: x.slice(0, i), desc: x.slice(i + 1).trim() };
  })
  .map(({ left, desc }) => {
    const types = /<(\??)(\w+)>$/.exec(left);
    if (!types) return { flagText: left, desc, arg: null };
    return { flagText: left.slice(0, types.index).trim(), desc, arg: { type: types[2], optional: !!types[1], default: types[2] === 'bool' ? false : '' } };
  })
  .map(({ flagText, desc, arg }) => {
    const flags = flagText.split(',').map(x => x.trim());
    if (flags.length === 1) {
      return { short: null, long: flags[0].slice(2), desc, arg };
    } else {
      return { short: flags[0].slice(1), long: flags[1].slice(2), desc, arg }
    }
  });

console.log(JSON.stringify(flags, null, 2));