qs.js

const reg = new RegExp("([^?=&]+)(=([^&]*))?", "g")

function qs (uri) {
  const obj = {}
  uri = uri.replace(/^.*\?/, '')
  uri.replace(reg, map)
  return obj

  function map (a0, a1, a2, a3) {
    obj[decodeURIComponent(a1)] = decodeURIComponent(a3)
  }
}

console.log(qs('http:///foo/bar/#hello?world=bar'))
console.log(qs('/foo/bar/#hello?world=bar&foo=hey'))
console.log(qs('/foo/bar/#hello?world=bar&foo=hey&bbbbuuuub_foo=oi'))

based off http://stevenbenner.com/2010/03/javascript-regex-trick-parse-a-query-string-into-an-object/

Output:

❯ node qs.js
{ world: 'bar' }
{ world: 'bar', foo: 'hey' }
{ world: 'bar', foo: 'hey', bbbbuuuub_foo: '"oi"' }

Final version:

const reg = new RegExp("([^?=&]+)(=([^&]*))?", "g")
const decodeURIComponent = window.decodeURIComponent

module.exports = qs

// decode a uri into a kv representation :: str -> obj
function qs (uri) {
  const obj = {}
  uri.replace(/^.*\?/, '').replace(reg, map)
  return obj

  function map (a0, a1, a2, a3) {
    obj[decodeURIComponent(a1)] = decodeURIComponent(a3)
  }
}

Here's a version without using a regular expression (not better, just different):

module.exports = (uri) => {
  const p = uri.indexOf('?')
  return p === -1 ? {} : uri.substring(p + 1).split('&').reduce((o, e) => {
    const p = e.indexOf('=')
    o[decodeURIComponent(e.substring(0, p))] = decodeURIComponent(e.substring(p + 1))
  }, {})
}

Ah, good to know… looks like query strings are "are often used to carry identifying information in the form of key=value pairs", but nothing binding (seems?). See: https://tools.ietf.org/html/rfc3986#section-3.4 So lack of foo=bar&foo=baz (lists) and foo[bar]=baz (objects) compared to qs is a perfectly valid choice. 👍