Modern JavaScript Features You Should Be Using (ES2020 to ES2025)

JavaScript gets a new edition every year. If you learned it a while ago, these additions will make your code shorter and safer.

Safer property access

const city = user?.address?.city;          // undefined instead of a crash
const limit = options.limit ?? 20;          // only falls back on null/undefined, not 0
settings.theme ??= 'light';                 // assign if missing

Arrays

const last = items.at(-1);                  // last element
const sorted = prices.toSorted((a, b) => a - b);  // returns a copy; prices unchanged
const updated = todos.with(2, { ...todos[2], done: true });
const lastError = logs.findLast((l) => l.level === 'error');
const byStatus = Object.groupBy(orders, (o) => o.status);

Objects and copying

const copy = structuredClone(state);        // deep copy, handles Dates, Maps, cycles
Object.hasOwn(obj, 'id');                   // safer than obj.hasOwnProperty('id')

Async helpers

const results = await Promise.allSettled(requests);   // never rejects; inspect each result
const fastest = await Promise.any(mirrors.map(fetch));
const { promise, resolve, reject } = Promise.withResolvers();
const value = await Promise.try(() => mightThrowOrReturnPromise());

ES2025 additions

// Set methods
const both = admins.intersection(editors);
const all = admins.union(editors);

// Iterator helpers: lazy map/filter/take on any iterator
const firstTen = numbers().filter((n) => n % 2 === 0).take(10).toArray();

// Escape user input for a RegExp
const re = new RegExp(RegExp.escape(searchTerm), 'i');

// JSON modules
import config from './config.json' with { type: 'json' };

Other gems

• Numeric separators: 1_000_000.
• String.prototype.replaceAll.
• Top-level await in modules.
• Private class fields: #balance.
• Array.fromAsync to collect async iterables.

Check support for your target browsers (MDN's compatibility tables help); the newest features may need a recent browser or Node.js version.