compilation error on cb

[tedyu]

Our node.js microservice is using sonic-boom@3.8.1

Currently I am facing this compilation error:

/opt/app/node_modules/sonic-boom/index.js:393
    cb?.()
       ^

SyntaxError: Invalid or unexpected token
    at Object.replacementCompile (/opt/app/node_modules/append-transform/index.js:60:13)
    at Module._extensions..js (node:internal/modules/cjs/loader:1308:10)

Initially I thought this was due to low node.js version. But node.js 18 is used.

Any hint is welcome.

[mahmoodhamdi]

This error is caused by append-transform (used by istanbul/nyc for code coverage) — it compiles the code with an older parser that does not support optional chaining (cb?.()), even though Node.js 18 supports it natively.

The ?.() syntax was introduced in Node.js 14+, but tools like append-transform intercept Module._extensions[".js"] and pass the source through their own compiler which may not understand newer syntax.

A few solutions:

1. Update your code coverage tooling — if you're using nyc/istanbul, upgrade to the latest version or switch to Node.js built-in --experimental-vm-modules + c8 for coverage:

   npm install -D c8
   npx c8 node your-app.js

2. Upgrade sonic-boom — sonic-boom@3.8.1 is quite old. Current versions use the same syntax but if your toolchain can't handle it, the root cause is still the parser.

3. Remove append-transform from your dependency chain. Check if a transitive dependency pulls it in:

   npm ls append-transform

The issue is not in sonic-boom itself — it's valid modern JavaScript. The real fix is in the tooling that intercepts module loading.