Better Stack Traces

Ever find yourself digging line-by-line through a Javascript stack trace
to find the "real" error?

Error: ENOENT, no such file or directory '/bad/file/path'
at Object.openSync (fs.js:230:18)
at Object.readFileSync (fs.js:120:15)
at readMyFile (/path/to/some/code/example.js:10:6)
at doStuff (/path/to/some/code/example.js:5:10)
at Object. (/path/to/some/code/example.js:13:1)
at Module._compile (module.js:441:26)
at Object..js (module.js:459:10)
at Module.load (module.js:348:31)

With better-stack-traces, you get inline code snippets instead:

Error: ENOENT, no such file or directory '/bad/file/path'
at Object.openSync (fs.js:230:18)
at Object.readFileSync (fs.js:120:15)
at readMyFile (/path/to/some/code/example.js:10:6)
──────────────────────────────────────────────────
8 »
9 » function readMyFile(filePath) {
10 » fs.readFileSync(filePath);
•••••••••••
11 » }
12 »
13 » doStuff(readMyFile)

at doStuff (/path/to/some/code/example.js:5:10)
───────────────────────────────────────────────
3 »
4 » function doStuff(readCallback) {
5 » return readCallback("/bad/file/path");
••••••••••••••
6 » }
7 »
8 »

at Object. (/path/to/some/code/example.js:13:1)
──────────────────────────────────────────────────────────
11 » }
12 »
13 » doStuff(readMyFile)
••••••

at Module._compile (module.js:441:26)
at Object..js (module.js:459:10)
at Module.load (module.js:348:31)

Usage

1. Install the module using npm install better-stack-traces
2. At the top of your code, require("better-stack-traces").register()
* Alternatively, require("better-stack-traces/register"). This is useful for
tools that have commandline options like --require in mocha.
3. Enjoy easier-to-read stack traces

Using better-stack-traces with CoffeeScript

If you develop with CoffeeScript,
better-stack-traces will automatically compile .coffee files when
rendering the trace. Maybe someday we will have
proper
line number mapping,
but until then better stack traces might help your sanity :)

Customizing the output

Stack traces not quite better enough? There are a few options to tweak the
output:

``javascript
require("better-stack-traces").register({
before: 2, // number of lines to show above the error
after: 3, // number of lines to show below the error
maxColumns: 80, // maximum number of columns to output in code snippets
collapseLibraries: /node_modules/ // omit code snippets from paths that match the given regexp (ignores node_modules by default)
})
`

If you want to get really fancy, take a look at the library itself. You can
subclass BetterStackTrace and register your customized subclass instead.

Related resources

If you find better-stack-traces useful, you might be interested in these:

* V8 Stack Trace API
* Tips for V8 stack formatting
* Long stack traces (for event handlers)

Contributors

- Wilker Lúcio (wilkerlucio)
- allow regex for collapseLibraries`