@azmr/core

Installation

pnpm add @azmr/core

Signal

A reactive value container. Any effect that reads .get() while active will re-run when the value changes.

import { Signal } from "@azmr/core";

const count = new Signal(0);
count.set(1);
console.log(count.get()); // 1
console.log(count.peek()); // 1 — reads without subscribing

effect

Runs a function immediately and re-runs whenever any Signal read inside it changes. Returns a disposer.

import { Signal, effect } from "@azmr/core";

const name = new Signal("Aroha");

const dispose = effect(() => {
  console.log(`Hello, ${name.get()}`);
});
// → Hello, Aroha

name.set("Tane");
// → Hello, Tane

computed

A read-only Signal whose value is derived from other Signals.

import { Signal, computed } from "@azmr/core";

const price = new Signal(100);
const gst = computed(() => price.get() * 0.15);

console.log(gst.get()); // 15
price.set(200);
console.log(gst.get()); // 30

Listen to a Signal from outside the reactive system — useful for bridging to React, Vue, or any non-reactive code.

import { Signal } from "@azmr/core";

const price = new Signal(100);

const unsubscribe = price.subscribe((value) => {
  console.log(`price changed to ${value}`);
});

price.set(200); // → price changed to 200

unsubscribe(); // stop listening

The scheduler uses a generation counter to prevent effects from running more than once per flush cycle. An effect that reads and writes the same signal will run at most twice — the re-queue is deduplicated, preventing unbounded loops.

const s = new Signal(0);

// Safe — deduplicated by the scheduler, never runs unboundedly
effect(() => {
  s.get();
  s.set(s.peek() + 1);
});

API Reference

`Signal<T>`

Method	Returns	Description
`get()`	`T`	Read value and subscribe current effect
`set(value)`	`void`	Update value and notify subscribers
`peek()`	`T`	Read value without subscribing
`subscribe(fn)`	`() => void`	Register a callback, returns unsubscribe function

Functions

Function	Description
`effect(fn)`	Run `fn` reactively, returns disposer
`computed(fn)`	Create a derived read-only Signal