error-stamp

Mutate a JS error object to include a stamp of current step.

Why

The main motivation for this module is for using Node.JS style callbacks. When passing the Error object, it contains the details of the sync call, but loses track of all async coming after.

This module solves this issue by adding to the trace additional "stamps" when used. For example, if before you handled errors like this:

if(err) {
    callback(err);
    return;
}   

Now you can get additional trace information by doing:

var stamp = require('error-stamp');

if(err) {
    stamp(err);
    callback(err);
    return;
}   

And since the function always return the input, there's a shorter version:

var stamp = require('error-stamp');

if(err) {
    callback(stamp(err));
    return;
}   

Before & After

Before using the module

node examples/example.js

/tmp/error-stamp/examples/example.js:42
        throw err;
        ^

Error
    at null._onTimeout (/tmp/error-stamp/examples/example.js:35:18)
    at Timer.listOnTimeout (timers.js:89:15)

After using the module

node examples/example_withstamps.js

/tmp/error-stamp/examples/example_withstamps.js:42
        throw err;
        ^

Error
    at ErrStamp /tmp/error-stamp/examples/example_withstamps.js:8:33
    at ErrStamp /tmp/error-stamp/examples/example_withstamps.js:23:36
    at null._onTimeout (/tmp/error-stamp/examples/example_withstamps.js:35:18)
    at Timer.listOnTimeout (timers.js:89:15)

API

errorStamp(err, [msg])

Mutate an Error object to include a stamp of current step.

Kind: global function

Param	Type	Description
err	Error	An object that inherits from Error.prototype .
[msg]	string	Optional. A message to add with the stamp.

errorStamp.setErrorPrefix(value)

Sets the error prefix used in each new line added to the trace. Default is "ErrStamp"

Kind: static method of errorStamp

Param	Type	Description
value	string	The value to set

Alternatives

Some other module tackle the same issue, among them:

• longjohn does the job, but as it has recommended- not intended on production environment (note it interferes with every asyc execution).
• async-stacktrace has greatly inspired this module, but it does more than just adding trace stamps (throw errors, call callbacks and conditionally create Error objects).

Notes

This module can also be used when handling errors with promises.