literate: typescript
@hackbg/konzola 
Makes console output more readable.
CJS/ESM support
This package includes 2 versions:
- CJS version for Node
- ESM version for browsers (incl. ESM-only bundlers such as Vite)
import * as KonzolaCJS from './konzola.cjs'
import * as KonzolaMJS from './konzola.browser.mjs'
import { ok, equal } from 'assert'
const testEach = x => [KonzolaCJS, KonzolaMJS].forEach(x)Console formatting
-
The methods log, info, warn, error and trace are augmented with colored prefixes.
-
The methods debug and trace pretty-print any objects that are passed to them.
-
[ ] TODO: Use console.table (in CLI) and HTML formatting (in browser) to print error boxes
testEach(({ CustomConsole })=>{
const log = new CustomConsole('CustomConsole')
log.log('hello\nworld')
log.info('FYI\nindent')
log.warn('beware\nof bugs!')
log.error('oops\n:(')
log.table([[123,456],[789,101112]])
log.debugEnabled = true
log.debug({pretty: 'printed'})
log.trace({this: 'too'})
})The console output is formatted as $NAME $LEVEL $ARGS, where $NAME is specified by the
constructor and is padded up to the length of the longest name of all CustomConsole instances.
testEach(({ CustomConsole })=>{
CustomConsole.indent = 0
new CustomConsole('Foo')
equal(CustomConsole.indent, 3)
new CustomConsole('FooBar')
equal(CustomConsole.indent, 6)
new CustomConsole('Baz')
equal(CustomConsole.indent, 6)
})Custom log events
By extending the CustomConsole class, you can define logging events.
This is meant as the first step towards converting a console.log-peppered codebase
to structured logging.
testEach(({ CustomConsole })=>{
class MyConsole extends CustomConsole {
myEvent (...params) {
console.info('My event:', ...params)
}
}
const log = new MyConsole('MyCustomConsole')
log.myEvent(1, 2, 3)
})Custom errors
By extending the CustomError class, you can easily define module-specific error classes.
This enables you to test for specific error conditions using the instanceof operator.
Names of defined errors are generated automatically, and you can pass a function that
generates the error message from the passed constructor parameters.
- [ ] TODO: Inherit from
EventEmitter, allowing structured log data to be emitted from custom logging functions - [ ] TODO: Third argument to
this.define, returning an object containing the properties that will be assigned to the error instance at construction. This allows for custom data to be attached to error instances.
testEach(({ CustomError })=>{
class AppError extends CustomError {
static InvalidInput = this.define('InvalidInput',
(value) => `${value} (${typeof value}) is not valid input.`)
static InvalidOutput = this.define('InvalidOutput')
}
const error1 = new AppError.InvalidInput('foo')
ok(error1 instanceof Error)
ok(error1 instanceof CustomError)
ok(error1 instanceof AppError)
ok(error1 instanceof AppError.InvalidInput)
equal(error1.constructor, AppError.InvalidInput)
equal(error1.constructor.name, 'InvalidInputAppError')
equal(error1.name, 'InvalidInputAppError')
equal(error1.message, 'foo (string) is not valid input.')
const error2 = new AppError.InvalidOutput('ignored')
ok(error2 instanceof Error)
ok(error2 instanceof CustomError)
ok(error2 instanceof AppError)
ok(error2 instanceof AppError.InvalidOutput)
equal(error2.constructor, AppError.InvalidOutput)
equal(error2.constructor.name, 'InvalidOutputAppError')
equal(error2.name, 'InvalidOutputAppError')
equal(error2.message, '')
})Other helpers
This package also exports the timestamp function, which returns a filename-friendly
timestamp in the format YYYYMMDD_HHMMSS:
import { equal } from 'assert'
testEach(({ timestamp }) => {
equal(timestamp(new Date("2020-05-12T23:50:21.817Z")), '20200512_235021')
})The packages table, colors, propmts and the non-broken version of prettyjson
are also reexported.