This library provides three iterable weak data structures for JavaScript, IterableWeakSet, IterableWeakMap, and WeakValueMap. These data structures are designed to work with objects as keys or values, and are useful when you need to store a collection of objects that may be garbage collected.
import { IterableWeakMap, IterableWeakSet, WeakValueMap, } from "@denostack/weakref"; const set = new IterableWeakSet(); const map = new IterableWeakMap(); const weakValueMap = new WeakValueMap();
Install
npm install weakref
import { IterableWeakMap, IterableWeakSet } from "weakref";
IterableWeakSet is a class that extends the WeakSet and Set classes in JavaScript, allowing you to create a set of objects that can be iterated over. Objects in the set are stored using weak references, which means that they can be garbage collected if they are no longer referenced elsewhere in the program.
Interface
class IterableWeakSet<T extends object> implements WeakSet<T>, Set<T> { constructor(values?: readonly T[] | null); constructor(iterable: Iterable<T>); }
Example
const set = new IterableWeakSet(); // create an object with a weak reference { const user = { id: 1, email: "[email protected]" }; set.add(user); } // end of scope, user will be garbage collected // force garbage collection if (global.gc) { global.gc(); } // check the set size console.log(set.size); // output: 0
IterableWeakMap is a class that extends the WeakMap and Map classes in JavaScript, allowing you to create a map of objects that can be iterated over. Keys in the map are stored using weak references, which means that they can be garbage collected if they are no longer referenced elsewhere in the program.
Interface
class IterableWeakMap<K extends object, V> implements WeakMap<K, V>, Map<K, V> { constructor(entries?: readonly (readonly [K, V])[] | null); constructor(iterable: Iterable<readonly [K, V]>); }
Example
const map = new IterableWeakMap(); // create an object with a weak reference { const user = { id: 1, email: "[email protected]" }; const metadata = { created: new Date() }; map.set(user, metadata); } // end of scope, user will be garbage collected // force garbage collection if (global.gc) { global.gc(); } // check the map size console.log(map.size); // output: 0
WeakValueMap is a class that allows you to create a map of non-object keys with weak references to object values. This is useful when you have a collection of non-object keys that you want to use to look up objects, and those objects may be garbage collected.
Interface
class WeakValueMap<K, V extends object> implements Map<K, V> { constructor(entries?: readonly (readonly [K, V])[] | null); constructor(iterable: Iterable<readonly [K, V]>); }
Example
const map = new WeakValueMap(); // create an object with a weak reference { const user = { id: 1, email: "[email protected]" }; map.set(user.id, user); } // end of scope, user will be garbage collected // force garbage collection if (global.gc) { global.gc(); } // check the map size console.log(map.size); // output: 0
- Python weakref my library is inspired by this library.
- MDN - JS WeakMap
- MDN - JS WeakSet
- MDN - JS WeakRef
- MDN - JS FinalizationRegistry