what-core

The reactive engine behind What Framework. Provides signals, fine-grained reactivity, components, hooks, and DOM rendering -- all without a virtual DOM diffing step.

Most users should install what-framework instead. what-core is the internal engine consumed by other What packages.

Install

npm install what-core

Reactive Primitives

import { signal, computed, effect, batch, untrack } from 'what-core';

const count = signal(0);

// Read
count();          // 0

// Write
count.set(5);
count.set(c => c + 1);

// Derived value
const doubled = computed(() => count() * 2);

// Side effects
effect(() => {
  console.log('Count:', count());
});

// Batch updates (effects run once at the end)
batch(() => {
  a.set(1);
  b.set(2);
});

// Read without subscribing
untrack(() => someSignal());
count.peek();

Hooks

React-compatible hooks backed by signals internally.

import {
  useState, useEffect, useMemo, useCallback,
  useRef, useReducer, useContext, createContext,
  onMount, onCleanup,
} from 'what-core';

const [count, setCount] = useState(0);

useEffect(() => {
  const id = setInterval(tick, 1000);
  return () => clearInterval(id);
}, []);

Components

import { mount, signal } from 'what-core';

function Counter() {
  const count = signal(0);
  return (
    <button onClick={() => count.set(c => c + 1)}>{count()}</button>
  );
}

mount(<Counter />, '#app');

Additional Modules

| Export path | Contents | |---|---| | what-core | Signals, hooks, components, store, forms, data fetching, animation, a11y, skeleton loaders | | what-core/render | Fine-grained rendering primitives (template, insert, spread, delegateEvents) | | what-core/jsx-runtime | JSX automatic runtime | | what-core/testing | Test utilities |

API Overview

Reactivity -- signal, computed, effect, batch, untrack, flushSync, createRoot

Rendering -- Fragment, html, mount, template, insert, spread, delegateEvents

Hooks -- useState, useSignal, useComputed, useEffect, useMemo, useCallback, useRef, useContext, useReducer, createContext, onMount, onCleanup, createResource

Components -- memo, lazy, Suspense, ErrorBoundary, Show, For, Switch, Match, Island, Portal

Store -- createStore, derived, atom

Data Fetching -- useSWR, useQuery, useInfiniteQuery, invalidateQueries, prefetchQuery

Forms -- useForm, useField, rules, zodResolver, Input, Select, Checkbox, ErrorMessage

Animation -- spring, tween, easings, useGesture, useTransition

Accessibility -- useFocusTrap, FocusTrap, announce, SkipLink, useRovingTabIndex, VisuallyHidden, useId

Scheduler -- scheduleRead, scheduleWrite, measure, mutate, onResize, onIntersect

Head -- Head, clearHead

Links

• Documentation
• GitHub
• Benchmarks

License

MIT