closure shine aikin da aka haɗa tare da viggae zuwa masu canji daga muhallin (lexical) scope dinsa. Saboda closures, aikin ciki yana ci gaba da samun iko zuwa masu canji na aiki na waje hatta bayan aiki na waje ya dawowa.
() {
count = ;
{
: ++count,
: count,
};
}
a = ();
b = ();
a.(); a.();
b.();
count ba zai iya samun daidai daga waje ba — kawai inc/get zasu iya ganin shi. Wannan shine kula da bayani da aka gina daga closure. Kuma kowane kira zuwa makeCounter() tana haifar da sabon, mai kanta scope.
for (var i = 0; i < 3; i++) {
setTimeout(() => console.log(i), 0); // prints 3, 3, 3 — all share one `i`
}
for (let i = 0; i < 3; i++) {
setTimeout(() => console.log(i), 0); // prints 0, 1, 2 — `let` is per-iteration
}
Tare da var, kowane callback ya rufe akan daidai i (wanda yayi 3 jiya da suka fara aiki). let yana bukatar sabon haɗi a kowane maimaita.
Closures suna ba da iko ga tsaro na jikin module, tunatarwa, currying, masu sarrafa abubuwan al'ada/kira waɗanda suke tunawa da karakoli, kuma kusan yadda React hooks (useState) ke ci gaba da suna tsakanin sadarwa.