edge-dynamic-code-evaluation.md

Dynamic code evaluation is not available in Middlewares or Edge API Routes

Why This Error Occurred

eval(), new Function() or compiling WASM binaries dynamically is not allowed in Middlewares or Edge API Routes. Specifically, the following APIs are not supported:

• eval()
• new Function()
• WebAssembly.compile
• WebAssembly.instantiate with a buffer parameter

Possible Ways to Fix It

You can bundle your WASM binaries using import:

import { NextResponse } from 'next/server'
import squareWasm from './square.wasm?module'

export default async function middleware() {
  const m = await WebAssembly.instantiate(squareWasm)
  const answer = m.exports.square(9)

  const response = NextResponse.next()
  response.headers.set('x-square', answer.toString())
  return response
}

In rare cases, your code could contain (or import) some dynamic code evaluation statements which can not be reached at runtime and which can not be removed by treeshaking. You can relax the check to allow specific files with your Middleware or Edge API Route exported configuration:

export const config = {
  runtime: 'edge', // for Edge API Routes only
  unstable_allowDynamic: [
    '/lib/utilities.js', // allows a single file
    '/node_modules/function-bind/**', // use a glob to allow anything in the function-bind 3rd party module
  ],
}

unstable_allowDynamic is a glob, or an array of globs, ignoring dynamic code evaluation for specific files. The globs are relative to your application root folder.

Be warned that if these statements are executed on the Edge, they will throw and cause a runtime error.