JavaScript hutumia ukusanyaji-takataka wa kiotomatiki (automatic garbage collection). Mkusanyaji hutumia algoriti ya mark-and-sweep: kuanzia kwenye mizizi (roots) (global object, call stack ya sasa), huweka alama kwa kila kitu kinachofikika (reachable), kisha huachilia huru kila kisichofikika. Hutaweza kamwe free() kwa mkono — lakini unaweza kwa bahati mbaya kuweka rejea hai, na kusababisha uvujaji.
// 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
}
Rejea kutoka mahali popote panapofikika (global, listener iliyo hai, closure, au node ya DOM iliyotenganishwa lakini bado inarejewa katika JS) huzuia object isikusanywe.
performance.memory; // rough heap size (Chrome)
// Chrome DevTools → Memory → take heap snapshots at two points and compare
Chukua heap snapshots kabla/baada ya kitendo; "retained size" inayoendelea kukua hufichua kile kisichoachiliwa huru.
const meta = new WeakMap(); // keys are weakly held — GC can collect them
meta.set(domNode, data); // doesn't prevent domNode from being garbage-collected
Programu zinazoendelea kwa muda mrefu (SPAs, Node servers) huanguka au hupungua kasi kutokana na uvujaji.
Marekebisho ni usafishaji wenye nidhamu — ondoa listeners/timers, weka mipaka kwa caches (LRU), epuka rejea zinazobaki, na tumia WeakMap/WeakSet kwa metadata isiyopaswa kuweka objects hai.
Maktaba ya maswali ya mahojiano ya IT yenye majibu ya kina — kutoka Junior hadi Senior.
Changia