Notes for "The Tyranny of Triple-Equals"

immutable-record.js

let lookupTable = Immutable.Map({})
export function record (fields) {
  let key = Immutable.Map(fields)	
  let storedValue = lookupTable.get(key)
  if (storedValue) { return storedValue }
  
  let newValue = Object.freeze({ ...fields })
  lookupTable = lookupTable.set(key, newValue)
  return newValue
}

tricking-deep-equality.js

const Foo = (() => {
  const PRIVATE = new WeakMap()
  return class Foo {
    value (...args) {
      if (args.length) {
        PRIVATE.set(this, args[0])
        return this
      }
      return PRIVATE.get(this)
    }
  }
})()
let x = new Foo()
x.value(1)
let y = new Foo()
y.value(2)
x.value === y.value // => true