A library to make errors.
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
:
function(message, data)
You'll typically do something like:
var makeError = require('makeerror') var UnknownFileTypeError = makeError( 'UnknownFileTypeError', 'The specified type is not known.' ) var er = UnknownFileTypeError()
er
will have a prototype chain that ensures:
er instanceof UnknownFileTypeError er instanceof Error
There is support for simple string substitutions like:
var makeError = require('makeerror') var UnknownFileTypeError = makeError( 'UnknownFileTypeError', 'The specified type "{type}" is not known.' ) var er = UnknownFileTypeError({ type: 'bmp' })
Now er.message
or er.toString()
will return 'The specified type "bmp" is not known.'
.
You can create simple hierarchies as well using the prototype
chain:
var makeError = require('makeerror') var ParentError = makeError('ParentError') var ChildError = makeError( 'ChildError', 'The child error.', { proto: ParentError() } ) var er = ChildError()
er
will have a prototype chain that ensures:
er instanceof ChildError er instanceof ParentError er instanceof Error