requireEnv()

Read a variable the app cannot run without. Returns a string or throws with the variable's name.

Import

import { requireEnv } from 'next-dynenv'

Signature

function requireEnv(key: string): string

Parameters

Parameter	Type	Description
key	string	Variable name. In the browser it must start with NEXT_PUBLIC_.

Returns

The value, typed string. requireEnv() reads through env(), so it follows the same server and browser rules.

Throws

When the value is undefined:

Required environment variable 'DATABASE_URL' is not defined.
Please set it in your environment or .env file.

In the browser, once window.__ENV exists, a key without the NEXT_PUBLIC_ prefix throws the env() prefix error first.

Behavior

Variable	Result
https://api.example.com	Returns the value
Set to an empty string	Returns ''
Not set	Throws

Only undefined fails. Validate content with envParsers.url() or envParsers.enum() when an empty or malformed value would also break the app.

Examples

Route handler

// app/api/orders/route.ts
import { requireEnv } from 'next-dynenv'

export async function GET() {
    const res = await fetch(`${requireEnv('NEXT_PUBLIC_API_URL')}/orders`, {
        headers: { Authorization: `Bearer ${requireEnv('API_SECRET_KEY')}` },
    })

    return Response.json(await res.json())
}

Config function

// lib/config.ts
import { requireEnv } from 'next-dynenv'

export function getConfig() {
    return {
        apiUrl: requireEnv('NEXT_PUBLIC_API_URL'),
        appName: requireEnv('NEXT_PUBLIC_APP_NAME'),
    }
}

Call it inside functions

Keep requireEnv() out of module scope. next build imports your route modules, so a top-level call throws during the build on any machine that lacks production variables, and building without them is how one image serves every environment.

Client component

'use client'

import { requireEnv } from 'next-dynenv'

export function SupportLink() {
    const appName = requireEnv('NEXT_PUBLIC_APP_NAME')

    return <a href="/support">Contact {appName} support</a>
}

Compared with env()

	env()	requireEnv()
Return type	string | undefined	string
Missing value	undefined or your default	Throws
Default value	Optional second argument	None
Use it for	Optional settings	Required settings

For typed values, the json(), url(), and enum() parsers also throw on missing values unless you pass a default. boolean(), number(), and array() fall back to defaults instead.

Related

• env() for optional values
• envParsers for typed values
• Troubleshooting for variables that come back undefined