useSignal

Creates a reactive cell holding one value: the low-level primitive useStore builds on.

Creates a reactive cell holding one value: the low-level primitive useStore builds on. Reads inside effects and memos subscribe them; writes notify them. Works at module scope.

Import#

import { useSignal } from "@shadow-js/core";

Signature#

function useSignal<T>(value: T, options?: SignalOptions<T>): [Accessor<T>, Setter<T>]

Parameters#

Name	Description
`value`	Initial value.
`options`	Equality override and a devtools name. Undefined uses the defaults.

Returns#

A [read, write] pair. The writer also accepts an updater (prev) => next, which runs untracked, and returns the value it stored.

Throws#

ShadowError WRITE_IN_MEMO from the writer, in development builds only, when it is called while a useMemo computation runs (unless that memo sets allowWrites).

Examples#

import { useSignal } from "@shadow-js/core";

const [count, setCount] = useSignal(0);
setCount((n) => n + 1);
console.log(count()); // 1