use-map

Create a reactive Map with typed helpers.


Package	`@vizejs/composable/use-map`
Own the source	`vize lib pull composable:use-map`
Runtime exports	`useMap`
Gzip budget	1280 B

Usage

import { useMap } from "@vizejs/composable/use-map";

Runtime contract

Utility	Category	Stability	SSR	Hydration	Cleanup	Targets	Host globals	Uses
`useMap`	state	experimental	safe	stable	none	web, server, worker, native, desktop, terminal	—	—

API

`useMap`

Create a reactive Map with typed helpers. Key and value types are inferred from the initial entries (useMap([["a", 1]]) is a Map<string, number>); pass type arguments for an initially empty map. Reads through get, has, and map are tracked per key, so an effect reading one key does not re-run when an unrelated key changes. Values are stored as-is (not deeply reactive). Purely synchronous state: safe during server rendering (no host globals, no timers) and nothing to dispose.

function useMap<Key = unknown, Value = unknown>( initial: Iterable<readonly [Key, Value]> = [], ): MapControls<Key, Value>

const counts = useMap<string, number>();
counts.update("clicks", (previous = 0) => previous + 1);

Types

`MapControls`

Reactive map wrapper returned by useMap.

Member	Type	Description
`map`	`ReadonlyMap<Key, Value>`	Read-only reactive view of the map. `get`, `has`, iteration, and `size` on this view are tracked per key. Values are stored shallowly.
`size`	`ComputedRef<number>`	Number of entries.
`entries`	`ComputedRef<readonly (readonly [Key, Value])[]>`	Snapshot of the entries in insertion order.
`get`	`(key: Key) => Value \| undefined`	Read the value for `key`. Reactive when read inside an effect.
`has`	`(key: Key) => boolean`	Whether `key` is present. Reactive when read inside an effect.
`set`	`(key: Key, value: Value) => void`	Store `value` under `key`.
`delete`	`(key: Key) => boolean`	Remove `key`.
`clear`	`() => void`	Remove every entry.
`update`	`(key: Key, updater: (previous: Value \| undefined) => Value) => Value`	Replace the value under `key` with the result of `updater`.
`getOrInsert`	`(key: Key, create: (key: Key) => Value) => Value`	Return the value under `key`, inserting `create(key)` first when absent.
`reset`	`() => void`	Restore the creation-time entries.