`fetch()` not working when node is running with `--jitless` flag set

[yanjiew1]

Version

v25.2.1

Platform

Microsoft Windows NT 10.0.26200.0 x64

Subsystem

No response

What steps will reproduce the bug?

1. Enter REPL by running node --jitless
2. Type await fetch('https://www.google.com');, and press Enter.

How often does it reproduce? Is there a required condition?

There is no required condition. The issue can always be reproduced when node is running with --jitless flag.

What is the expected behavior? Why is that the expected behavior?

A response object should be returned.

What do you see instead?

fetch() failed because WebAssembly isn’t available. Node’s fetch() implementation (via undici) depends on WebAssembly, so it can’t run without it.

This is the error message.

Uncaught TypeError: fetch failed
    at node:internal/deps/undici/undici:15845:13
    at process.processTicksAndRejections (node:internal/process/task_queues:103:5)
    at async REPL1:1:33 {
  [cause]: ReferenceError: WebAssembly is not defined
      at lazyllhttp (node:internal/deps/undici/undici:6531:9)
      at connectH1 (node:internal/deps/undici/undici:7056:26)
      at node:internal/deps/undici/undici:8604:93
      at TLSSocket.<anonymous> (node:internal/deps/undici/undici:2939:13)
      at Object.onceWrapper (node:events:622:28)
      at TLSSocket.emit (node:events:508:28)
      at TLSSocket.emit (node:domain:552:15)
      at TLSSocket.onConnectSecure (node:internal/tls/wrap:1667:8)
      at TLSSocket.emit (node:events:508:28)
      at TLSSocket.emit (node:domain:552:15)

Additional information

No response

[mcollina]

@yanjiew1 the HTTP parser used by fetch() is implemented in WebAssembly for ease of distribution. You can see the same parser used for Node.js core and Undici.

What's your usecase?

The main reason we use WebAssembly is maintenance convenience, as it allows us to not use any of the private APIs of Node.js and support all platforms without any additional binaries.

This can be changed, but not without significant work.