@percy/logger

Common logger used throughout the Percy CLI and SDKs.

• Usage
  • logger()
  • logger.loglevel()
  • logger.format()
  • logger.query()

Usage

import logger from '@percy/logger'

const log = logger('foobar')

log.info('info message')
log.error('error message')
log.warn('warning message')
log.debug('debug message')
log.deprecated('deprecation message')

logger([debug])

Creates a group of logging functions that will be associated with the provided debug label. When debug logging is enabled, this label is printed with the [percy:*] label and can be filtered via the PERCY_DEBUG environment variable.

PERCY_DEBUG="one:*,*:a,-*:b"

logger.loglevel('debug')

logger('one').debug('test')
logger('one:a').debug('test')
logger('one:b').debug('test')
logger('one:c').debug('test')
logger('two').debug('test')
logger('two:a').debug('test')

// only logs from the matching debug string are printed
//=> [percy:one] test
//=> [percy:one:a] test
//=> [percy:one:c] test
//=> [percy:two:a] test

logger.loglevel([level][, flags])

Sets or retrieves the log level of the shared logger. If the second argument is provided, level is treated as a fallback when all logging flags are false. When no arguments are provided, the method will return the current log level of the shared logger.

logger.loglevel('info', { verbose: true })
logger.loglevel() === 'debug'

logger.loglevel('info', { quiet: true })
logger.loglevel() === 'warn'

logger.loglevel('info', { silent: true })
logget.loglevel() === 'silent'

logger.loglevel('info')
logger.loglevel() === 'info'

logger.format(message, debug[, level])

Returns a formatted message depending on the provided level and logger's own log level. When debugging, the debug label is added to the prepended [percy:*] label.

logger.format('foobar', 'test')
//=> [percy] foobar

logger.loglevel('debug')
logger.format('foobar', 'test', warn')
//=> [percy:test] foobar (yellow for warnings)

logger.query(filter)

Returns an array of logs matching the provided filter function.

let logs = logger.query(log => {
  return log.level === 'debug' &&
    log.message.match(/foobar/)
})