Vote for Espruino features!

I guess you are right @Gordon in terms of performance impact. But RAM is still an issue i guess because its very precious :)

I have a sweet little example for the Map vs. Object point @opichals made before.
Should be self-explanatory.

'use strict';

let sequence = (...map) => (ok, nok) => {
        map = new Map(map.map(e => Array.isArray(e) ? e : [e]));
        ok(Array.from(map.keys()).reduce((all, prm) => {
            return all.then(res => prm.then(data => res.set(prm, (map.get(prm) || (() => data))(data))).catch(nok));
        }, Promise.resolve(map)));
    };

let add = num => num + 1;
let mul = num => num * 2;
let addPromise = num => Promise.resolve(num);
let mulPromise = num => Promise.resolve(num);

let adding = addPromise(10);
let multing = mulPromise(20);

let map = [adding,[multing, mul]];

new Promise(sequence(...map)).then(result => {
    console.log('result', {addResult: result.get(adding), mulResult: result.get(multing)});
}).catch(console.log.bind(null, 'error'));