First item from a Map on JavaScript ES2015

Use the Map.prototype.entries function, like this

const m = new Map();
m.set('key1', {})
m.set('keyN', {})

console.log(m.entries().next().value); // [ 'key1', {} ]

If you want to get the first key, then use Map.prototype.keys, like this

console.log(m.keys().next().value); // key1

Similarly if you want to get the first value, then you can use Map.prototype.values, like this

console.log(m.values().next().value); // {}

The reason why we have to call next() on the returned values is that, all those functions return iterators. Read more about the iteration protocol here.

For the specific example you are wondering about, destructuring would be perfect.

let m = new Map();
m.set('key1', {});
m.set('key2', {});

let [[, obj]] = m;

e.g.

let [pair] = m;
let [key, obj] = pair;

is one option to destructure and then grab the value, but the easier option would be

let [obj] = m.values();