---
title: "isClientOutdated()"
description: "Server-side utility to check if a client's version is outdated."
canonical_url: "https://nuxtseo.com/docs/skew-protection/nitro-api/is-client-outdated"
last_updated: "2026-05-06T21:35:01.647Z"
---

**Type:** `function isClientOutdated(event: H3Event): boolean`

Returns `true` when the client's version cookie doesn't match the current `buildId`. Use this in server-side Nitro routes, middleware, and API handlers to detect outdated clients.

## API

```ts
import { isClientOutdated } from 'nuxt-skew-protection/server'

function isClientOutdated(event: H3Event): boolean
```

### Arguments

- `event: H3Event`: The H3 event object from the request handler.

### Returns

- `boolean`: `true` if the client version doesn't match the current buildId, `false` otherwise.

## Examples

### Throwing an Error in API Route

```ts
// server/api/data.ts
import { isClientOutdated } from 'nuxt-skew-protection/server'

export default defineEventHandler(async (event) => {
  // Check if client is outdated
  if (isClientOutdated(event)) {
    throw createError({
      statusCode: 409,
      message: 'Client version outdated. Please refresh.'
    })
  }

  // Proceed with API logic
  const data = await fetchData()
  return data
})
```

### Add Header in Middleware

```ts
// server/middleware/check-version.ts
import { isClientOutdated } from 'nuxt-skew-protection/server'

export default defineEventHandler((event) => {
  const path = event.path

  // Only check on API routes
  if (!path.startsWith('/api/')) {
    return
  }

  if (isClientOutdated(event)) {
    const userVersion = getSkewProtectionCookie(event)
    console.log(`Outdated client detected: ${userVersion}`)

    // Add header to inform client
    setResponseHeader(event, 'X-Client-Outdated', 'true')
  }
})
```