How to show useful error backtrace on nodejs es module?

Question

I try to use es module with nodejs, but seems that it's error backtrace dosen't show where the error was thrown?

// copy and rename to `a.cjs` and `a.mjs`
console.log("hi")
throw "err"

node --trace-uncaught a.cjs
node --trace-uncaught a.mjs

CommonJS

[kkocdko@fedora kblog]$ node --trace-uncaught a.cjs
hi

/home/kkocdko/misc/code/kblog/a.cjs:2
throw "err"
^
err
Thrown at:
    at /home/kkocdko/misc/code/kblog/a.cjs:2:1
    at Module._compile (node:internal/modules/cjs/loader:1103:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1155:10)
    at Module.load (node:internal/modules/cjs/loader:981:32)
    at Module._load (node:internal/modules/cjs/loader:822:12)
    at executeUserEntryPoint (node:internal/modules/run_main:77:12)
    at node:internal/main/run_main_module:17:47

ES Module

[kkocdko@fedora kblog]$ node --trace-uncaught a.mjs
hi

node:internal/process/esm_loader:94
    internalBinding('errors').triggerUncaughtException(
                              ^
err
Thrown at:
    at loadESM (node:internal/process/esm_loader:94:31)

The CommonJS version reported the position of error, but ES Module does not. This cause debuging to be difficult. How to show useful error backtrace on nodejs es module?

Answer 1

Throwing an Error populates the stack, throwing a String does not.

throw new Error('err')

$ node a.mjs
file:///so73742023/a.mjs:7
throw new Error('err')
      ^

Error: err
    at file:///so73742023/a.mjs:7:7
    at ModuleJob.run (node:internal/modules/esm/module_job:193:25)
    at async Promise.all (index 0)
    at async ESMLoader.import (node:internal/modules/esm/loader:528:24)
    at async loadESM (node:internal/process/esm_loader:91:5)
    at async handleMainPromise (node:internal/modules/run_main:65:12)

Don't throw strings.

Answer 2

Have you tried console.error OR Error.captureStackTrace ? If these don't work for you then you could try using the node-stack-trace module, a power full module to track call stacks.