Messing with ES6 Map + Generator

generator-to-map.js

const ENDKEY = Symbol('endOfMap');

function* simpleGen() {
  let counter = 0
  while (counter++ < 3) {
   yield [counter, true]
  }
  
  yield [ENDKEY, false]
}

let gen = simpleGen() // iterable!
let map = new Map(gen) // takes an iterable!

for (let [key, value] of map.entries()) {
  console.log(key, value)
}

// 0 true
// 1 true
// 2 true
// Symbol(endOfMap) false