Paadhé JavaScript ngatur memori lan kepiye rembesan bisa kedadeyan?

Question

Accepted Answer

JavaScript nggunakake **automatic garbage collection**. Kolèktor nggunakake algoritma **mark-and-sweep**: mula saka roots (global object, call stack saiki), nandha kabèh sing **karacut**, banjur nglumpukaké kabèh sing ora karacut. Sampeyan ora perlu `free()` manual — nanging bisa kasusah jupuk referensi tetep urip, nyebabake rembesan.

## Papat sumber rembesan klasik

```js
// 1. Unbounded globals / caches that never shrink
window.cache = window.cache || {};
window.cache[id] = bigObject; // grows forever

// 2. Forgotten event listeners
el.addEventListener("click", handler);
// must call el.removeEventListener("click", handler) when done

// 3. Forgotten timers
const id = setInterval(tick, 1000);
// must clearInterval(id)

// 4. Closures capturing large objects longer than needed
function outer() {
  const huge = new Array(1e6);
  return () => huge.length; // keeps `huge` alive as long as the closure lives
}
```

Referensi saka saindhenging panggonan karacut (global, listener idup, closure, node DOM sing copot nanging isih dirujuk ing JS) njaga obyek supaya ora bisa dikumpulaké.

## Diagnosa rembesan

```js
performance.memory; // rough heap size (Chrome)
// Chrome DevTools → Memory → take heap snapshots at two points and compare
```

Tanggo heap snapshots sadurungé/sawisé aksi; "retained size" sing tansah kuwat nuduhake apa sing ora dilerèna.

## Alat kanggo nyegah ngenep obyek

```js
const meta = new WeakMap(); // keys are weakly held — GC can collect them
meta.set(domNode, data);    // doesn't prevent domNode from being garbage-collected
```

## Yen apa iya penting

App sing mlaku suwe (SPAs, server Node) kasil ngadhepe ndhedhere utawa alon-alon saka rembesan.

Fiksané yaiku pembersihan disiplin — copot listeners/timers, cache terikat (LRU), iwas referensi sing suwe, lan nggunakake `WeakMap`/`WeakSet` kanggo metadata sing kudu ora njaga obyek tetep urip.