await-trace

(Ugly) solution for complete stack traces in async/await. Production ready.

We needed complete stack traces that has a very low performance overhead. This mini-module is created as a response to the closed issue Missing stack traces from async functions after the first await. I hope that NodeJS team will create a native solution.

It may be ugly but you can refactor your codebase quickly to use this module AND also you can quickly refactor it back to the original async/await.

Installation

npm install await-trace --save

Usage

Replace your await promise with await nab(() => E(), promise). For example, convert this:

async function sideEffect(dummy){
  const data = await fetchData()
  return await updateData(data)
}

to this:

const {nab, E} = require('await-trace')

async function sideEffect(dummy){
  const data = await nab(() => E(), fetchData())
  return await nab(() => E(), updateData(data))
}

Quick refactoring

If you want to quickly refactor your code, I recommend you to use a replace tool that accepts regex patterns. I have done my refactoring using Jetbrains IDEs:

Find: await\s(.*)(\)$) Replace: await nab(() => E(), $1$2)

Explanation

• E() is an alias to Error(). Module exports Err() too.
• The lazy initialization of error via () => E() is necessary in order not to degrade performance.
• NodeJS builds stack trace from the place where an error is created. That's why you have to pass E() in every single nab()

Caveats

• I don't know how to make it work with setTimeout(). With promises you'll be fine.
• For stack traces longer than 10 lines use --stack-trace-limit flag, e.g.: node --stack-trace-limit=100 index.js

Invitation

NodeJS is great for development and this is just a pain in the ass in otherwise wonderful ecosystem! We'll be glad if you find any improvements (make a PR. ;) or if you offer a better solution than this one.