@brooswit/sundry

A toolbox of small, well-tested TypeScript utilities. Each one is independent; add more as you go.

watch(fn, onChange, intervalMs, options?)

Polls fn on an interval and calls onChange(next, prev) whenever the value changes. Returns a stop().

import { watch } from "@brooswit/sundry";

const stop = watch(
  () => fs.statSync("config.json").mtimeMs,   // sync or async
  (next, prev) => console.log("changed", prev, "→", next),
  1000,
);
// ...later
stop();   // idempotent

• The first call is a baseline — it captures the initial value and does not fire onChange.
• Change is detected by a stable, order-independent hash, so {a:1,b:2} → {b:2,a:1} is not a change.
• Adaptive cadence. Each tick runs the interval timer and fn at once; the next tick begins when both finish — max(interval, fn-duration). A fast fn keeps a steady interval; a slow fn runs back-to-back with no gap and no dropped ticks. A tick never overlaps the next.
• fn may be sync or async.
• A throw/reject skips that tick (no change, baseline unchanged). Pass options.onError to observe it.
• options: onError?, hash? (override the hash), setTimeout?/clearTimeout? (inject timers, e.g. for tests).

Also exported: hashValue, stableStringify, fnv1a.

Development

bun run check       # generate + typecheck + tests + coverage ≥90%   (what CI runs)
bun test

Every change to src/ needs a CHANGELOG.md entry and a version bump (CI enforces it); merges to main publish to npm with provenance.