fromEntries and Object Spread

Object.fromEntries is the reverse of entries. Object spread { ...a, ...b } shallow-merges; later keys win. Use that for defaults + per-instance overrides — keep a base options object, then { ...base, origin: "right", delay: 500 } for one call without mutating the shared defaults.

Merge overrides into defaults, or rebuild from entries.

Important JavaScript

const defaults = { theme: "light", pageSize: 10, notifications: true };
const patch = { theme: "dark", pageSize: 25 };

const merged = { ...defaults, ...patch };
// { theme: "dark", pageSize: 25, notifications: true }
// later spread wins on conflicting keys

// Same idea for animation / library options:
const base = { distance: "50px", duration: 1000, origin: "bottom" };
const asideOpts = { ...base, origin: "right", delay: 500 };

const pairs = Object.entries(merged);
const again = Object.fromEntries(pairs);
// same plain object shape

const tweaked = Object.fromEntries(
  pairs.map(([key, value]) => {
    if (key === "pageSize") {
      return [key, Number(value)];
    }
    return [key, value];
  })
);