viewport setting in metadata is not working correctly

[hi-paul]

Link to the code that reproduces this issue

https://codesandbox.io/p/devbox/priceless-rgb-2hcyms?file=%2Fapp%2Flayout.tsx&workspaceId=12540e31-6959-44ce-a050-2ec2eabe3bda

To Reproduce

Add code to root layout.tsx

export const metadata = {
  viewport: { width: 1920 }
}

Current vs. Expected behavior

current: <meta name="viewport" content="width=device-width, initial-scale=1" />

expected: <meta name="viewport" content="width=1920" />

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 23.2.0: Wed Nov 15 21:53:18 PST 2023; root:xnu-10002.61.3~2/RELEASE_ARM64_T6000
Binaries:
  Node: 20.11.0
  npm: 10.2.4
  Yarn: 1.22.19
  pnpm: 8.14.1
Relevant Packages:
  next: 13.5.6
  eslint-config-next: 13.5.6
  react: 18.2.0
  react-dom: 18.2.0
  typescript: 4.9.5
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

App Router, Metadata (metadata, generateMetadata, next/head)

Which stage(s) are affected? (Select all that apply)

next dev (local), next build (local), next start (local), Vercel (Deployed), Other (Deployed)

Additional context

No response

[hi-paul]

I recently upgraded vercel version and didn't realize that the viewport for metadata was deprecated. Thanks for letting me know🙏 @ttaerrim

When I applied it as you suggested, it looks like <meta name="viewport" content="width=1920, initial-scale=1">, but can't I remove the ,initial-scale=1?

[ttaerrim]

Sorry, I deleted my comment by mistake.

try to add code to root layout.tsx

export const viewport: Viewport = {
  width: 1920
}

But I don't know how to initialize viewport tag to none.

[devjiwonchoi]

Hi, initial-scale set to 1 will not harm since it is the default value.
Since the default value is mapped internally, you cannot explicitly remove it from your source.

next.js/packages/next/src/lib/metadata/default-metadata.tsx

Lines 6 to 15 in 65d699e

	export function createDefaultViewport(): ResolvedViewport {
	return {
	// name=viewport
	width: 'device-width',
	initialScale: 1,
	// visual metadata
	themeColor: null,
	colorScheme: null,
	}
	}

Also, it is recommended to follow the Codemods so that you don't need to explicitly export viewport.

ref: https://nextjs.org/docs/app/building-your-application/upgrading/codemods#use-viewport-export

[hi-paul]

Actually, what I'm working on now is to show the desktop in 1920 width on the mobile screen. Before upgrading nextjs, it was <meta name="viewport" content="width=1920" /> and it worked as I wanted, but now it doesn't work when it's set to <meta name="viewport content="width=1920, initial-scale=1" />.

The default value of initial-scale is 1, but I figured that its presence had an impact, so I set initial-scale to -1 and it worked fine.

Thank you for your kind explanation and help in resolving the issue.

[github-actions]

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