makeerror

A library to make errors.

Basics

Makes an Error constructor function with the signature below. All arguments are optional, and if the first argument is not a String, it will be assumed to be data:

1function(message, data)

You'll typically do something like:

1var makeError = require('makeerror')
2var UnknownFileTypeError = makeError(
3  'UnknownFileTypeError',
4  'The specified type is not known.'
5)
6var er = UnknownFileTypeError()

er will have a prototype chain that ensures:

1er instanceof UnknownFileTypeError
2er instanceof Error

Templatized Error Messages

There is support for simple string substitutions like:

1var makeError = require('makeerror')
2var UnknownFileTypeError = makeError(
3  'UnknownFileTypeError',
4  'The specified type "{type}" is not known.'
5)
6var er = UnknownFileTypeError({ type: 'bmp' })

Now er.message or er.toString() will return 'The specified type "bmp" is not known.'.

Prototype Hierarchies

You can create simple hierarchies as well using the prototype chain:

1var makeError = require('makeerror')
2var ParentError = makeError('ParentError')
3var ChildError = makeError(
4  'ChildError',
5  'The child error.',
6  { proto: ParentError() }
7)
8var er = ChildError()

er will have a prototype chain that ensures:

1er instanceof ChildError
2er instanceof ParentError
3er instanceof Error