ES6+ Features Every Developer Should Actually Be Using in 2026

ES6 (2015) and the yearly releases since added a lot of syntax. Some of it changed how correct code is by default; some of it is convenience. Worth knowing the difference.

The ones that fix real correctness problems

• let/const over var — block scoping fixes the closure-in-a-loop bug covered earlier in this series, by default, not as an opt-in.
• Optional chaining (?.) — `user?.address?.city` returns undefined instead of throwing when `address` doesn't exist, replacing a wall of manual `&&` guards with one that's actually readable.
• Nullish coalescing (??) — `value ?? 'default'` falls back only on null/undefined, unlike `||`, which also (usually wrongly) falls back on `0`, `''`, and `false`.
• Destructuring — `const { name, email } = user` makes it structurally obvious which fields a function actually depends on, at the call site and in the function signature both.

The one that changes how you structure async code

// Spread + destructuring together, in a real reducer pattern
function updateUser(state, updates) {
  return { ...state, ...updates, updatedAt: Date.now() };
}

The spread operator (`...`) is what makes immutable update patterns — used constantly in Redux reducers and React state updates — concise enough to actually write by hand instead of reaching for a mutation and a bug later.

The ones that are genuinely just convenience

Template literals (`` `Hello, ${name}` ``) and arrow functions are worth using for readability, but they don't change what's correct the way block scoping or optional chaining do — arrow functions' one behavioral difference (no own `this`) is a real gotcha covered in the next post, not a pure convenience.

The practical filter

Learn the ones that change what bugs are even possible first — scoping, optional chaining, nullish coalescing, destructuring. The rest is worth knowing, but it's polish, not foundation.