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Every value, error and\n flag flows through signals straight to the DOM.\n- 🎯 **Signal-first.** Field state _is_ a signal you can drop anywhere:\n ``, `{form.watch(\"email\")}`, `{errorSignal}`.\n- 🧩 **Two APIs.** Imperative `register()` **and** declarative `` / ``.\n- 🛡 **Fully typed.** Dot-path autocompletion (`user.address.city`, `items.0.name`).\n- ✅ **Validation.** Built-in rules **plus** schema resolvers (Zod / Valibot / Yup).\n- 🌲 **Tiny & tree-shakeable.** ESM + CJS, resolvers in separate entry points.\n\n## Installation\n\n```bash\nnpm install @dmytromykhailiuk/preact-signal-hook-forms\n```\n\nRequires **Node.js ≥ 18** and the peer dependencies every Preact app already has:\n\n| Peer dependency | Version |\n| ----------------- | --------------------- |\n| `preact` | `>=10.11.0` |\n| `@preact/signals` | `>=1.2.0` or `^2.0.0` |\n\nSchema libraries (`zod`, `valibot`, `yup`) are **optional** — install one only if\nyou use its resolver.\n\n## Table of contents\n\n- [Quick start](#quick-start)\n- [Why signals?](#why-signals)\n- [Core concepts](#core-concepts)\n - `[useForm(options)](#useformoptions)`\n - `[register(name, rules?)](#registername-rules)`\n - [Reading values:](#reading-values-values-watch-getvalues) `values`[,](#reading-values-values-watch-getvalues) `watch`[,](#reading-values-values-watch-getvalues) `getValues`\n - [Writing values:](#writing-values-setfieldvalue-setvalue) `setFieldValue`[,](#writing-values-setfieldvalue-setvalue) `setValue`\n - `[reset(values?, options?)](#resetvalues-options)`\n - `[formState](#formstate)`\n - [Showing errors](#showing-errors)\n- [Validation](#validation)\n- [Declarative components](#declarative-components)\n- [Dynamic lists —](#dynamic-lists--usefieldarray) `useFieldArray`\n- [Other hooks](#other-hooks)\n- [Migrating from react-hook-form](#migrating-from-react-hook-form)\n- [API reference](#api-reference)\n- [Development](#development)\n- [License](#license)\n\n## Quick start\n\n```tsx\nimport { useForm } from \"@dmytromykhailiuk/preact-signal-hook-forms\";\n\nfunction LoginForm() {\n // 👇 This function runs exactly ONCE.\n const form = useForm<{ email: string; password: string }>({\n defaultValues: { email: \"\", password: \"\" },\n mode: \"onBlur\",\n });\n\n const onSubmit = form.handleSubmit((values) => {\n console.log(values); // fully typed { email, password }\n });\n\n return (\n \n );\n}\n```\n\n## Why signals?\n\nreact-hook-form is fast because it is _uncontrolled_ — it avoids re-renders by\nreading the DOM through refs. This library reaches the same goal from the other\ndirection: **the field value is a signal, and Preact binds signals directly to\nthe DOM** (as an attribute or a text node). The value is fully controlled, yet\nnothing re-renders.\n\n## Core concepts\n\n### `useForm(options)`\n\nCreates a form controller that stays **stable for the component's lifetime**\n(options are read once, on the first render). All options:\n\n| Option | Type | Default |\n| ------------------ | ------------------ | -------- | -------------- | ------------ | ------ | ------------ |\n| `defaultValues` | `Partial` | `{}` |\n| `mode` | `\"onChange\" | \"onBlur\" | \"onSubmit\" | \"onTouched\" | \"all\"` | `\"onSubmit\"` |\n| `reValidateMode` | `\"onChange\" | \"onBlur\" | \"onSubmit\"` | `\"onChange\"` |\n| `resolver` | `Resolver` | – |\n| `criteriaMode` | `\"firstError\" | \"all\"` | `\"firstError\"` |\n| `shouldFocusError` | `boolean` | `true` |\n| `shouldUnregister` | `boolean` | `false` |\n| `delayError` | `number` (ms) | – |\n\n`delayError` debounces the _appearance_ of a new error: validation still runs\nimmediately, but the message is held back for the given delay so it never\nflashes mid-keystroke. Clearing is always instant — the moment the field\nbecomes valid the error disappears, and a pending message is cancelled.\n`setError` bypasses the delay.\n\n`mode` decides when a field is validated **for the first time**;\n`reValidateMode` takes over once the field already shows an error (or the form\nwas submitted). The default pair — validate on submit, re-validate on every\nchange — means users aren't nagged while typing, but errors disappear the\nmoment the input becomes valid.\n\n### `register(name, rules?)`\n\nReturns props to spread onto a DOM element:\n\n```tsx\n\n```\n\nThe returned `value` is a **read-only signal bound directly to the element's**\n`value` **attribute**. Nullish model values surface as `\"\"` so an empty field\nrenders empty (never the string `\"undefined\"`); read the actual model value\nwith `getValues(name)` or `watch(name)`.\n\nCheckbox / radio / file inputs are driven through the `ref` (their `checked` /\n`files` state) — spreading `register` just works:\n\n```tsx\n\n\n\n```\n\n### Reading values: `values`, `watch`, `getValues`\n\n- `form.values` → a `ReadonlySignal` holding the **whole model**.\n Render it directly to track the form without a re-render.\n- `form.watch(name?)` → a `ReadonlySignal` of one field (or the whole model\n when called with no argument — the same signal as `form.values`).\n- `form.getValues(name?)` → a plain **snapshot** (uses `.peek()`, no\n subscription). Use it inside event handlers.\n\n```tsx\n
{JSON.stringify(form.values.value, null, 2)}
; // reactive\nconst email = form.getValues(\"email\"); // one-off read\n```\n\n### Writing values: `setFieldValue`, `setValue`\n\n- `form.setFieldValue(name, value, options?)` → write **one** field.\n- `form.setValue(values, options?)` → replace the **whole model**. Paths\n missing from `values` become `undefined`, array fields collapse to `[]`, and\n values for paths that were never registered as fields are kept.\n\nBoth accept `{ shouldValidate, shouldDirty, shouldTouch }`.\n\n`setValue` swaps the values but leaves `defaultValues` untouched, so the form\ngoes **dirty** — it is not a reset. Use `form.reset(values?)` when you want the\nnew values to become the baseline that `isDirty` compares against.\n\n> **Note:** this differs from react-hook-form, where `setValue` is the\n> single-field writer. Here that is `setFieldValue`.\n\n### `reset(values?, options?)`\n\nRestores the model to `defaultValues` (or to `values`, which then **becomes**\nthe new default). Field arrays are realigned: items added via `append` that the\ndefaults don't contain are dropped, and an array with no entry in the defaults\nresets to `[]`. With no `defaultValues` at all, the model resets to an empty\nobject.\n\nOptions: `keepValues`, `keepDirty`, `keepErrors`, `keepTouched`,\n`keepIsSubmitted`, `keepSubmitCount`.\n\n`keepDirty` preserves the user's in-progress edits through the reset: every\nfield that is dirty (differs from the _old_ defaults) keeps its current value,\nwhile clean fields adopt the new ones — the classic \"background refetch must\nnot clobber unsaved edits\" case. Kept fields stay dirty against the new\nbaseline. This includes field arrays: structural changes and item edits\nsurvive, except edits to items the new defaults no longer contain.\n\n```tsx\nform.reset(); // back to the original defaults\nform.reset(serverData); // adopt server data as the new baseline\nform.reset(serverData, { keepDirty: true }); // refetch without losing edits\nform.reset(undefined, { keepValues: true }); // clear errors/touched, keep values\n```\n\n### `formState`\n\nEvery property is a signal — drop it straight into JSX:\n\n```tsx\n;\n{\n form.formState.isDirty.value && Unsaved changes;\n}\n```\n\n`errors`, `isDirty`, `isValid`, `isValidating`, `isSubmitting`, `isSubmitted`,\n`isSubmitSuccessful`, `submitCount`, `dirtyFields`, `touchedFields`,\n`defaultValues`, `shared`.\n\n`shared` is a **writable** scratch signal (`Signal<{ [key: string]: any }>`)\nthe library never touches: use it to pass ad-hoc state between distant fields\nor components that already hold the form control, without wiring up your own\ncontext.\n\n```tsx\nform.formState.shared.value = { activeSection: \"billing\" };\n```\n\n### Showing errors\n\n`getFieldState(name)` returns reactive signals per field: `error`, `isDirty`,\n`isTouched`, `isValidating`, `invalid`.\n\n```tsx\nimport { computed } from \"@preact/signals\";\n\nconst nameError = computed(\n () => form.getFieldState(\"name\").error.value?.message\n);\n// Rendered as a live text node — no re-render:\n{nameError};\n```\n\n## Validation\n\n### Built-in rules\n\n```tsx\nform.register(\"email\", {\n required: \"Email is required\",\n pattern: { value: /^[^@]+@[^@]+$/, message: \"Invalid email\" },\n minLength: { value: 5, message: \"Too short\" },\n});\n```\n\n`required`, `min`, `max`, `minLength`, `maxLength`, `pattern`, `validate`,\n`deps`, `disabled`, plus `valueAsNumber` / `valueAsDate` / `setValueAs`.\n\n### Custom validators\n\n`validate` takes a function receiving the **field value** and the **whole\nmodel** — return `true`/`undefined` when valid, or a message string:\n\n```tsx\nform.register(\"confirm\", {\n validate: (value, values) =>\n value === values.password || \"Passwords do not match\",\n});\n```\n\nAsync validators are awaited (`validate: async (v) => …`), and out-of-order\nresults are race-safe: when a newer validation starts while an older one is\nstill in flight, the stale run's result is discarded **and its** `AbortSignal`\n**fires** — pass it to `fetch` so the server request is actually cancelled, not\njust ignored:\n\n```tsx\nform.register(\"username\", {\n validate: async (value, _values, signal) => {\n const res = await fetch(`/api/check?u=${value}`, { signal });\n const { taken } = await res.json();\n return taken ? \"Already taken\" : true;\n },\n});\n```\n\nThe signal also aborts when the field is reset, cleared or unregistered. A\nvalidator that rejects after its signal aborted (the normal `fetch` behaviour)\nends quietly. The same guard applies to async resolvers — a custom resolver\nreceives the signal as its second argument. To run several named\nchecks, pass a record — the failing key becomes `error.type`, and with\n`criteriaMode: \"all\"` every failure is collected into `error.types`:\n\n```tsx\nform.register(\"username\", {\n validate: {\n noSpaces: (v) => !v.includes(\" \") || \"No spaces allowed\",\n lowercase: (v) => v === v.toLowerCase() || \"Must be lowercase\",\n },\n});\n```\n\nCross-field checks need `deps` — \"when **this** field changes, re-validate\n**those**\":\n\n```tsx\nform.register(\"password\", { deps: [\"confirm\", \"passwordHint\"] });\n```\n\n> **Note:** configuring a `resolver` disables built-in rules (including\n> `validate`) entirely — the schema becomes the single source of truth.\n\n### Schema resolvers\n\nResolvers ship as separate entry points, so the schema library never lands in\nyour main bundle:\n\n```tsx\nimport { useForm } from \"@dmytromykhailiuk/preact-signal-hook-forms\";\nimport { zodResolver } from \"@dmytromykhailiuk/preact-signal-hook-forms/resolvers/zod\";\nimport { z } from \"zod\";\n\nconst schema = z.object({\n email: z.string().email(),\n age: z.number().min(18),\n});\n\nconst form = useForm({ resolver: zodResolver(schema) });\n```\n\nAlso available: `…/resolvers/valibot` and `…/resolvers/yup`.\n\n## Declarative components\n\n### `\n```\n\n### ``\n\nRender-prop or auto-binding, using the `control` prop or a surrounding\n`