docs: general docs updates

docs/config.json

@@ -156,8 +156,16 @@
               "to": "framework/react/guides/react-native"
             },
             {
-              "label": "SSR/TanStack Start/Next.js",
-              "to": "framework/react/guides/ssr"
+              "label": "TanStack Start",
+              "to": "framework/react/guides/tanstack-start"
+            },
+            {
+              "label": "Next.js",
+              "to": "framework/react/guides/nextjs"
+            },
+            {
+              "label": "Remix",
+              "to": "framework/react/guides/remix"
             },
             {
               "label": "Debugging",
@@ -418,10 +426,6 @@
               "label": "Functions / useForm",
               "to": "framework/react/reference/functions/useForm"
             },
-            {
-              "label": "Functions / useTransform",
-              "to": "framework/react/reference/functions/useTransform"
-            },
             {
               "label": "Types / FieldComponent",
               "to": "framework/react/reference/type-aliases/FieldComponent"

docs/framework/angular/guides/submission-handling.md

@@ -102,3 +102,22 @@ export class AppComponent {
   })
 }
 ```
+
+> In a situation where you want to be able to submit in an invalid state `canSubmitWhenInvalid` boolean flag can be provided to useForm.
+
+```angular-ts
+import { injectForm } from '@tanstack/angular-form';
+
+export class AppComponent {
+  form = injectForm({
+    defaultValues: {
+      data: '',
+    },
+    canSubmitWhenInvalid: true,
+    onSubmit: async ({ value }) => {
+      // Do something with the values
+      console.log(value)
+    },
+    });
+}
+```

docs/framework/react/guides/arrays.md

@@ -52,6 +52,10 @@ Finally, you can use a subfield like so:
 </form.Field>
 ```
 
+## Why Index as Key?
+
+You may notice that these examples use `key={i}` the array index as the key prop. React's documentation generally advises _against_ using array indices as keys when items can be reordered or deleted. TanStack Form is an exception to this rule. Because field names in TanStack Form arrays are index-based, using the array index as `key` is required, it keeps React component instances, form store state, and field names in sync.
+
 ## Full Example
 
 ```jsx

docs/framework/react/guides/nextjs.md

@@ -0,0 +1,162 @@
+---
+id: nextjs
+title: TanStack Form - NextJs
+---
+
+## Using TanStack Form in a Next.js App Router
+
+> Before reading this section, it's suggested you understand how React Server Components and React Server Actions work. [Check out this blog series for more information](https://playfulprogramming.com/collections/react-beyond-the-render)
+
+This section focuses on integrating TanStack Form with `Next.js`, particularly using the `App Router` and `Server Actions`.
+
+### Next.js Prerequisites
+
+- Start a new `Next.js` project, following the steps in the [Next.js Documentation](https://nextjs.org/docs/getting-started/installation).
+- Install `@tanstack/react-form-nextjs`
+- Install any [form validator](./validation#validation-through-schema-libraries) of your choice. [Optional]
+
+## App Router integration
+
+Let's start by creating a `formOption` that we'll use to share the form's shape across the client and server.
+
+```ts shared-code.ts
+import { formOptions } from '@tanstack/react-form-nextjs'
+
+// You can pass other form options here
+export const formOpts = formOptions({
+  defaultValues: {
+    firstName: '',
+    age: 0,
+  },
+})
+```
+
+Next, we can create [a React Server Action](https://playfulprogramming.com/posts/what-are-react-server-components) that will handle the form submission on the server.
+
+```ts action.ts
+'use server'
+
+import {
+  ServerValidateError,
+  createServerValidate,
+} from '@tanstack/react-form-nextjs'
+
+import { formOpts } from './shared-code'
+
+// Create the server action that will infer the types of the form from `formOpts`
+const serverValidate = createServerValidate({
+  ...formOpts,
+  onServerValidate: ({ value }) => {
+    if (value.age < 12) {
+      return 'Server validation: You must be at least 12 to sign up'
+    }
+  },
+})
+
+export default async function someAction(prev: unknown, formData: FormData) {
+  try {
+    const validatedData = await serverValidate(formData)
+    console.log('validatedData', validatedData)
+    // Persist the form data to the database
+    // await sql`
+    //   INSERT INTO users (name, email, password)
+    //   VALUES (${validatedData.name}, ${validatedData.email}, ${validatedData.password})
+    // `
+  } catch (e) {
+    if (e instanceof ServerValidateError) {
+      return e.formState
+    }
+
+    // Some other error occurred while validating your form
+    throw e
+  }
+
+  // Your form has successfully validated!
+}
+```
+
+Finally, we'll use `someAction` in our client-side form component.
+
+```tsx client-component.tsx
+'use client'
+
+import { useActionState } from 'react'
+import {
+  initialFormState,
+  mergeForm,
+  useForm,
+  useStore,
+  useTransform,
+} from '@tanstack/react-form-nextjs'
+
+import someAction from './action'
+import { formOpts } from './shared-code'
+
+export const ClientComp = () => {
+  const [state, action] = useActionState(someAction, initialFormState)
+
+  const form = useForm({
+    ...formOpts,
+    transform: useTransform((baseForm) => mergeForm(baseForm, state!), [state]),
+  })
+
+  const formErrors = useStore(form.store, (formState) => formState.errors)
+
+  return (
+    <form action={action as never} onSubmit={() => form.handleSubmit()}>
+      {formErrors.map((error) => (
+        <p key={error as string}>{error}</p>
+      ))}
+
+      <form.Field
+        name="age"
+        validators={{
+          onChange: ({ value }) =>
+            value < 8 ? 'Client validation: You must be at least 8' : undefined,
+        }}
+      >
+        {(field) => {
+          return (
+            <div>
+              <input
+                name={field.name} // must explicitly set the name attribute for the POST request
+                type="number"
+                value={field.state.value}
+                onChange={(e) => field.handleChange(e.target.valueAsNumber)}
+              />
+              {field.state.meta.errors.map((error) => (
+                <p key={error as string}>{error}</p>
+              ))}
+            </div>
+          )
+        }}
+      </form.Field>
+      <form.Subscribe
+        selector={(formState) => [formState.canSubmit, formState.isSubmitting]}
+      >
+        {([canSubmit, isSubmitting]) => (
+          <button type="submit" disabled={!canSubmit}>
+            {isSubmitting ? '...' : 'Submit'}
+          </button>
+        )}
+      </form.Subscribe>
+    </form>
+  )
+}
+```
+
+### useTransform
+
+you may have noticed util function `useTransform` being used throughout these examples, it's primary responsibility is the merging of the server and client state. Under the hood it is a useCallback whose deps are that of the server state, when the server state changes it will automatically patch the client state.
+
+## debugging
+
+> If you get the following error in your Next.js application:
+>
+> ```typescript
+> x You're importing a component that needs `useState`. This React hook only works in a client component. To fix, mark the file (or its parent) with the `"use client"` directive.
+> ```
+>
+> This is because you're not importing server-side code from `@tanstack/react-form-nextjs`. Ensure you're importing the correct module based on the environment.
+>
+> [This is a limitation of Next.js](https://github.com/phryneas/rehackt). Other meta-frameworks will likely not have this same problem.

docs/framework/react/guides/remix.md

@@ -0,0 +1,158 @@
+---
+id: remix
+title: TanStack Form - Remix
+---
+
+## Using TanStack Form in Remix
+
+> Before reading this section, it's suggested you understand how Remix actions work. [Check out Remix's docs for more information](https://remix.run/docs/en/main/discussion/data-flow#route-action)
+
+### Remix Prerequisites
+
+- Start a new `Remix` project, following the steps in the [Remix Documentation](https://remix.run/docs/en/main/start/quickstart).
+- Install `@tanstack/react-form-start`
+- Install any [form validator](./validation#validation-through-schema-libraries) of your choice. [Optional]
+
+## Remix integration
+
+Let's start by creating a `formOption` that we'll use to share the form's shape across the client and server.
+
+```tsx routes/_index/route.tsx
+import { formOptions } from '@tanstack/react-form-remix'
+
+// You can pass other form options here
+export const formOpts = formOptions({
+  defaultValues: {
+    firstName: '',
+    age: 0,
+  },
+})
+```
+
+Next, we can create [an action](https://remix.run/docs/en/main/discussion/data-flow#route-action) that will handle the form submission on the server.
+
+```tsx routes/_index/route.tsx
+import {
+  ServerValidateError,
+  createServerValidate,
+  formOptions,
+} from '@tanstack/react-form-remix'
+
+import type { ActionFunctionArgs } from '@remix-run/node'
+
+// Create the server action that will infer the types of the form from `formOpts`
+const serverValidate = createServerValidate({
+  ...formOpts,
+  onServerValidate: ({ value }) => {
+    if (value.age < 12) {
+      return 'Server validation: You must be at least 12 to sign up'
+    }
+  },
+})
+
+export async function action({ request }: ActionFunctionArgs) {
+  const formData = await request.formData()
+  try {
+    const validatedData = await serverValidate(formData)
+    console.log('validatedData', validatedData)
+    // Persist the form data to the database
+    // await sql`
+    //   INSERT INTO users (name, email, password)
+    //   VALUES (${validatedData.name}, ${validatedData.email}, ${validatedData.password})
+    // `
+  } catch (e) {
+    if (e instanceof ServerValidateError) {
+      return e.formState
+    }
+
+    // Some other error occurred while validating your form
+    throw e
+  }
+
+  // Your form has successfully validated!
+}
+```
+
+Finally, the `action` will be called when the form submits.
+
+```tsx
+// routes/_index/route.tsx
+import { Form, useActionData } from '@remix-run/react'
+import { mergeForm, useForm, useStore } from '@tanstack/react-form'
+import {
+  ServerValidateError,
+  createServerValidate,
+  formOptions,
+  initialFormState,
+  useTransform,
+} from '@tanstack/react-form-remix'
+
+export default function Index() {
+  const actionData = useActionData<typeof action>()
+
+  const form = useForm({
+    ...formOpts,
+    transform: useTransform(
+      (baseForm) => mergeForm(baseForm, actionData ?? initialFormState),
+      [actionData],
+    ),
+  })
+
+  const formErrors = useStore(form.store, (formState) => formState.errors)
+
+  return (
+    <form method="post" onSubmit={() => form.handleSubmit()}>
+      {formErrors.map((error) => (
+        <p key={error as string}>{error}</p>
+      ))}
+
+      <form.Field
+        name="age"
+        validators={{
+          onChange: ({ value }) =>
+            value < 8 ? 'Client validation: You must be at least 8' : undefined,
+        }}
+      >
+        {(field) => {
+          return (
+            <div>
+              <input
+                name="age"
+                type="number"
+                value={field.state.value}
+                onChange={(e) => field.handleChange(e.target.valueAsNumber)}
+              />
+              {field.state.meta.errors.map((error) => (
+                <p key={error as string}>{error}</p>
+              ))}
+            </div>
+          )
+        }}
+      </form.Field>
+      <form.Subscribe
+        selector={(formState) => [formState.canSubmit, formState.isSubmitting]}
+      >
+        {([canSubmit, isSubmitting]) => (
+          <button type="submit" disabled={!canSubmit}>
+            {isSubmitting ? '...' : 'Submit'}
+          </button>
+        )}
+      </form.Subscribe>
+    </form>
+  )
+}
+```
+
+### useTransform
+
+you may have noticed util function `useTransform` being used throughout these examples, its primary responsibility is the merging of the server and client state. Under the hood it is a useCallback whose deps are that of the server state, when the server state changes it will automatically patch the client state.
+
+```tsx
+const form = useForm({
+  ...formOpts,
+  transform: useTransform(
+    (baseForm) => mergeForm(baseForm, actionData ?? initialFormState),
+    [actionData],
+  ),
+})
+```