Deep Freezing a JS object

freeze.js

"use strict";

function deepFreeze(obj) {
	// Freeze properties first. Then freeze self.
	const properties = Object.getOwnPropertyNames(obj);

	// Iterate over the properties and get their values.
	// Check if the value if not null and is an object itself.
	// If so, recursively freeze it.
	for (const property of properties) {
		const value = obj[property];

		if (value && typeof value === "object") {
			deepFreeze(value);
		}
	}

	return Object.freeze(obj);
}

const spidey = deepFreeze({
	name: {
		first: "Peter",
		last: "Parker",
	},
	alias: "Spiderman",
	profession: "Photographer",
	villains: ["Green Goblin", "Electro", "Venom", "Mysterio"],
});

spidey.name.middle = "Benjamin";
spidey.villains.push("Doc Ock");

console.log(spidey);