TypeScript

Inertia provides first-class TypeScript support. You may configure global types using declaration merging, and pass generics to hooks and router methods for type-safe props, forms, and state management.

Using pnpm

Due to pnpm's strict dependency isolation, @inertiajs/core is not accessible at node_modules/@inertiajs/core. Instead, it's nested inside .pnpm/, which prevents TypeScript module augmentation from resolving the module.

You may fix this by configuring pnpm to hoist the package. Add the following to your .npmrc file and run pnpm install.

public-hoist-pattern[]=@inertiajs/core

Alternatively, you may add @inertiajs/core as a direct dependency in your project.

pnpm add @inertiajs/core

Global Configuration

You may configure Inertia's types globally by augmenting the InertiaConfig interface in the @inertiajs/core module. This is typically done in a global.d.ts file in your project's root or types directory.

// global.d.ts
import '@inertiajs/core'

declare module '@inertiajs/core' {
  export interface InertiaConfig {
    sharedPageProps: {
      auth: { user: { id: number; name: string } | null }
      appName: string
    }
    flashDataType: {
      toast?: { type: 'success' | 'error'; message: string }
    }
    errorValueType: string[]
    layoutProps: {
      title: string
      showSidebar: boolean
    }
    namedLayoutProps: {
      app: { title: string; theme: 'light' | 'dark' }
      content: { padding: string; maxWidth: string }
    }
  }
}

NOTE

The import statement (or export {}) is required to make this file a module. Without it, declare module replaces the module definition instead of augmenting it. Your tsconfig.json also needs to include .d.ts files, so make sure a pattern like "@/**/*.d.ts" is present in the include array.

Shared Page Props

The sharedPageProps option defines the type of data that is shared with every page in your application. With this configuration, page.props.auth and page.props.appName will be properly typed everywhere.

sharedPageProps: {
  auth: { user: { id: number; name: string } | null }
  appName: string
}

Flash Data

The flashDataType option defines the type of flash data in your application.

flashDataType: {
  toast?: { type: 'success' | 'error'; message: string }
}

Error Values

By default, validation error values are typed as string. You may configure TypeScript to expect arrays instead for Rails' default (with model.errors) — multiple errors per field.

errorValueType: string[]

Layout Props

The layoutProps option types the data accepted by setLayoutProps(). The namedLayoutProps option types the data accepted by setLayoutProps('name', props), keyed by layout name.

layoutProps: {
  title: string
  showSidebar: boolean
}
namedLayoutProps: {
  app: {
    title: string
    theme: 'light' | 'dark'
  }
  content: {
    padding: string
    maxWidth: string
  }
}

With this configuration, setLayoutProps({ title: 'Dashboard' }) is type-checked, and setLayoutProps('app', { theme: 'dark' }) validates both the layout name and its props.

You may also pass a generic type parameter directly to setLayoutProps for ad-hoc typing without configuring the global InertiaConfig interface.

setLayoutProps<{ custom: string }>({ custom: 'value' })
setLayoutProps<{ collapsed: boolean }>('sidebar', { collapsed: true })

Page Components

You may type the import.meta.glob result for better type safety when resolving page components.

import { createInertiaApp } from '@inertiajs/vue3'
import type { DefineComponent } from 'vue'

createInertiaApp({
  resolve: (name) => {
    const pages = import.meta.glob<DefineComponent>('../pages/**/*.vue')
    return pages[`../pages/${name}.vue`]()
  },
  // ...
})

Page Props

You may type page-specific props by passing a generic to usePage(). These are merged with your global sharedPageProps, giving you autocomplete and type checking for both shared and page-specific data.

<script setup lang="ts">
import { usePage } from '@inertiajs/vue3'

const page = usePage<{
  posts: { id: number; title: string }[]
}>()
</script>

Form Helper

The form helper accepts a generic type parameter for type-safe form data and error handling. This provides autocomplete for form fields and errors, and prevents typos in field names.

<script setup lang="ts">
import { useForm } from '@inertiajs/vue3'

const form = useForm<{
  name: string
  email: string
  company: { name: string }
}>({
  name: '',
  email: '',
  company: { name: '' },
})
</script>

Nested Data and Arrays

Form types fully support nested objects and arrays. You may access and update nested fields using dot notation, and error keys are automatically typed to match.

import { useForm } from '@inertiajs/react'

const form = useForm<{
  user: { name: string; email: string }
  tags: { id: number; label: string }[]
}>({
  user: { name: '', email: '' },
  tags: [],
})

Form Component

Available since:@inertiajs/core:3.0.0

The <Form> component accepts a generic type parameter for type-safe slot props. In React, you may pass the generic directly. In Vue and Svelte, you may use the createForm helper to create a typed form component.

<script setup lang="ts">
import { createForm } from '@inertiajs/vue3'

interface UserForm {
  name: string
  email: string
}

const TypedForm = createForm<UserForm>()
</script>

<template>
  <TypedForm action="/users" method="post" #default="{ errors }">
    <input type="text" name="name" />
    <div v-if="errors.name">{{ errors.name }}</div>
    <button type="submit">Create User</button>
  </TypedForm>
</template>

The generic provides autocomplete and type checking for the errors object, setError, clearErrors, and other slot props that reference form fields.

useFormContext

Available since:@inertiajs/core:3.0.0

The useFormContext() function also accepts a generic type parameter, providing type-safe access to the form context from child components.

import { useFormContext } from '@inertiajs/react'

const form = useFormContext<UserForm>()

HTTP Helper

The useHttp hook accepts two generic type parameters: the form data type and an optional default response type.

import { useHttp } from '@inertiajs/react'

interface UserForm {
  name: string
  email: string
}

interface UserResponse {
  id: number
  name: string
}

const http = useHttp<UserForm, UserResponse>({ name: '', email: '' })

Per-Request Response Types

Each HTTP method accepts its own generic type parameter, allowing you to override the response type on a per-call basis. This is useful when different endpoints return different response shapes.

interface OrderResponse {
  orderId: string
  total: number
}

// Override the response type per request...
const user: UserResponse = await http.post<UserResponse>('/api/users')
const order: OrderResponse = await http.get<OrderResponse>('/api/orders/123')
const submitted: UserResponse = await http.submit<UserResponse>(
  'post',
  '/api/users',
)

// The onSuccess callback is also typed...
await http.post<UserResponse>('/api/users', {
  onSuccess: (response) => {
    console.log(response.id, response.name)
  },
})

Remembering State

The useRemember hook accepts a generic type parameter for type-safe local state persistence, providing autocomplete and ensuring values match the expected types.

<script setup lang="ts">
import { useRemember } from '@inertiajs/vue3'

const filters = useRemember<{
  search: string
  status: 'active' | 'inactive' | 'all'
}>({
  search: '',
  status: 'all',
})
</script>

Restoring State

The router.restore() method accepts a generic for typing state restored from history.

import { router } from '@inertiajs/react'

interface TableState {
  sortBy: string
  sortDesc: boolean
  page: number
}

const restored = router.restore<TableState>('table-state')

if (restored) {
  console.log(restored.sortBy)
}

Router Requests

Router methods accept a generic for typing request data, providing type checking for the data being sent.

import { router } from '@inertiajs/react'

interface CreateUserData {
  name: string
  email: string
}

router.post<CreateUserData>('/users', {
  name: 'John',
  email: '[email protected]',
})

Scoped Flash Data

The router.flash() method accepts a generic for typing page or section-specific flash data, separate from the global flashDataType configuration.

import { router } from '@inertiajs/react'

router.flash<{ paymentError: string }>({ paymentError: 'Card declined' })

Client-Side Visits

The router.push() and router.replace() methods accept a generic for typing client-side visit props.

import { router } from '@inertiajs/react'

interface UserPageProps {
  user: { id: number; name: string }
}

router.push<UserPageProps>({
  component: 'Users/Show',
  url: '/users/1',
  props: { user: { id: 1, name: 'John' } },
})

router.replace<UserPageProps>({
  props: (current) => ({
    ...current,
    user: { ...current.user, name: 'Updated' },
  }),
})