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Convert ES6 Map to Object Literal
let map = new Map();
map.set("a", 1);
map.set("b", 2);
map.set("c", 3);
let obj = Array.from(map).reduce((obj, [key, value]) => (
Object.assign(obj, { [key]: value }) // Be careful! Maps can have non-String keys; object literals can't.
), {});
console.log(obj); // => { a: 1, b: 2, c: 3 }
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Major performance hit when you create a new object (with Object.assign) inside every iteration.

Because you're creating a new object literal when you call Array.reduce(fn, {}), you can safely mutate that accumulator object from within the reducer function.

This is WAYYYYY faster:

let obj = Array.from(map).reduce((obj, [key, value]) => {
  obj[key] = value;
  return obj;
}, {});

Unfortunately, you'll never know because gist doesn't send comment notifications... I hope someone finds this comment and it helps them. Email me if it does, so I can be notified this helped someone 😉

this one helped me.

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vjpr commented Sep 9, 2021

If a value in the map can be an array of maps you need:

const toObject = (map = new Map) => {
  if (!(map instanceof Map)) return map
  return Object.fromEntries(Array.from(map.entries(), ([k, v]) => {
    if (v instanceof Array) {
      return [k,]
    } else if (v instanceof Map) {
      return [k, toObject(v)]
    } else {
      return [k, v]

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