Surprising lte (<=) and gte (>=) operator results in JavaScript for null, object, and undefined

null.js

// 9 Sep 2017, following
// https://twitter.com/AbinavSeelan/status/903935309871812610
// which explores the surprising `(null >= 0) == true`

// Not only is it surprising, it's bi-directional

console.log([
  // zero case
  null <= 0,
  null >= 0,
  0 <= null,
  0 >= null,

  // empty string
  null <= '',
  null >= '',
  '' >= null,
  '' <= null,

  // boolean
  null <= false,
  null >= false,
  false <= null,
  false >= null
].join(', '));

// true, true, true, true, true, true, true, true, true, true, true, true, true, true

object.js

// 9 Sep 2017
// following
// https://twitter.com/bmeurer/status/906593961430712320

// 2 different objects are different references, so...
console.log([
  {} < {},
  {} == {},
  {} === {},
].join(', '));

// false, false, false

// but...
console.log([
  {} <= {},
  {} >= {},
].join(', '));

// true, true

undefined.js

// 9 Sep 2017
// following
// https://twitter.com/bmeurer/status/906605033483108357

// should be true because null *is* null...
console.log([
  null <= null,
  null >= null
].join(', '));

// true, true

// should be true because undefined *is* undefined, but...
console.log([
  void 0 <= void 0,
  void 0 >= void 0,
  undefined <= undefined,
  undefined >= undefined,
].join(', '));

// false, false, false, false

JavaScript is weird