[FrozenCow]

You can check the 2nd and 3rd groups when using /(^\/foo\/bar$)|(^\/foo\/bar\/\d+$)/:

    > /(^\/foo\/bar$)|(^\/foo\/bar\/\d+$)/.exec('/foo/bar')
    [ '/foo/bar',
      '/foo/bar',
      undefined,
      index: 0,
      input: '/foo/bar' ]

    > /(^\/foo\/bar$)|(^\/foo\/bar\/\d+$)/.exec('/foo/bar/3')
    [ '/foo/bar/3',
      undefined,
      '/foo/bar/3',
      index: 0,
      input: '/foo/bar/3' ]

EDIT: Markdown differences.