// Sets
var s = new Set();
s.add("hello").add("goodbye").add("hello");
s.size === 2;
s.has("hello") === true;

// Maps
var m = new Map();
m.set("hello", 42);
m.set(s, 34); // <- use an object as a key!
m.get(s) == 34;

// Sets 
var values = [1, 1, 1, 1, 2], set = {};
values.forEach(addToSet(set));
//...
var testValue = 1;
if (values[testValue]) {
    console.log('found ' + testValue);
}

function addToSet(set) {
    return function(value) {
        set[value] = true;
    };
}

// Sets
var s = new Set([1, 1, 1, 1, 2]);
//...
var testValue = 1;
if (s.has(testValue)) {
     console.log('found ' + testValue);
}

($.Deferred() considered harmful)

function timeout(duration = 0) {
    return new Promise((resolve, reject) => {
        setTimeout(resolve, duration);
    })
}

var p = timeout(1000).then(() => {
    return timeout(2000);
}).then(() => {
    throw new Error("hmm");
}).catch(err => {
    return Promise.all([timeout(100), timeout(200)]);
})

Promise.race(iterable)
Promise.reject(reason)
Promise.resolve(value)

Object.assign(target, ...sources)

var obj = { a: 1 };
var copy = angular.extend({}, obj);
console.log(copy); // { a: 1 }

Copies enumerable and own properties from a source object to a target object. It uses [[Get]] on the source and [[Set]] on the target, so it will invoke getters and setters.

var obj = { a: 1 };
var copy = Object.assign({}, obj);
console.log(copy); // { a: 1 }

//Supports multiple source objects
var a = { a: 1 }, b = { b: 1 }, c = { c: 1};
var merged = Object.assign({}, a, b, c);

Object.is(value1, value2)

Almost the same as === with the following exceptions:

• treats the number values -0 and +0 as not equal
• treats Number.NaN as equal to NaN.