JS: Object.defineProperties

Object.defineProperties(obj, {key1: descriptor1}, {key2: descriptor2},…)

Create properties or modify existing properties.

Return the modified obj.

The descriptor1, descriptor2, etc are property descriptors.

[see JS: Property Descriptor]

[see JS: Property Attributes, writable, enumerable, configurable]

// create a object
const yy = {};

// add 2 properties, with their attributes
Object.defineProperties(
    yy,
    {
        x1:{ value : 1, writable: true, enumerable: true, configurable: true},
        x2:{ value : 2, writable: true, enumerable: true, configurable: true}
    }
);

console.log(yy);                // { x1: 1, x2: 2 }

To create/modify only 1 property, use Object.defineProperty

[see JS: Object.defineProperty]

Create/Add Getter/Setter Properties

Object.defineProperties(obj, {pkey1, { get: function, enumerable: false, configurable: true }}, {pkey2, …},…)

[see JS: Getter/Setter Properties]

Reference

ECMAScript® 2016 Language Specification#sec-object.defineproperties