logger

↓ Members.

↓ Methods.

module:logger

Description:

  • Logging utility

    Default mode is to use util.inspect and output to stdout

    Syslog mode can log to local or remote syslog with customizable facility and level

    JSON mode will output an object with predefined properties first then the rest will be put inside the data array

    {"level":"LOG","date":"2026-05-10T18:22:16.066Z","now":1778437336066,"role":"node","pid":71942, "data": ["shutdownServer:", "api", "node", "server", "closed"] }
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Example
logger.setLevel("info")
logger.log("log")             // visible
logger.info("info")           // visible
logger.debug("debug")         // not visible
logger.error("error")         // visible

logger.setLevel("debug")
logger.debug("debug")         // visible

logger.setLevel("info")
logger.setDebugFilter("custom")
logger.debug("debug")         // still not visible
logger.debug("custom")        // visible

Members

(static) date :string

Description:

  • default date format is $BKJS_LOG_DATE or local or iso or utc or none

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Default Value:
  • iso

(static) filters :object

Description:

  • debugging filters enabled, can be set via $BKJS_LOG_FILTER

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(static) inspectArgs :object

Description:

  • defaults for util.inspect

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(static) json :boolean

Description:

  • if true the outout will be a JSON object

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Default Value:
  • false

(static) level :int

Description:

  • current logging level, can be set via $BKJS_LOG_LEVEL

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Default Value:
  • 0(WARN)

(static) levels :object

Description:

  • levels sorted by priorities: ERROR, WARN, LOG, INFO, DEBUG, DEV

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(static) oneline :boolean

Description:

  • if true newlines will be replaced with spaces,

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Default Value:
  • false

(static) pid :string

Description:

  • pid is $BKJS_LOG_PID or the current process pid

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Default Value:
  • process.pid

(static) role :string

Description:

  • default role is $BKJS_LOG_ROLE if present

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(static) separator :string

Description:

  • concat argumenrs with this separator @default

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Default Value:
  • space

(static) tag :string

Description:

  • default tag is $BKJS_LOG_TAG if present

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Methods

(static) debug(…args)

Description:

  • Log with DEBUG level, enabled debug filter will be logged if matched

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Parameters:
Name Type Attributes Description
args ...any <repeatable>

(static) dev(…args)

Description:

  • Log with DEV level

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Parameters:
Name Type Attributes Description
args ...any <repeatable>

(static) dump()

Description:

  • Raw output using util.format

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(static) error(…args)

Description:

  • Log with ERROR level

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Parameters:
Name Type Attributes Description
args ...any <repeatable>

(static) info(…args)

Description:

  • Log with INFO level

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Parameters:
Name Type Attributes Description
args ...any <repeatable>

(static) inspect(level, args) → {string}

Description:

  • Called by logger methods to perform input formatting and cleaning, calls default or installed inspector

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Parameters:
Name Type Description
level string

current logging level
args Array.<any>

items to output
Returns:
Type Description
string
  • formatted output

(static) log(…args)

Description:

  • Log with LOG level

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Parameters:
Name Type Attributes Description
args ...any <repeatable>

(static) logger(level, …args)

Description:

  • A generic logger method, safe, first arg is supposed to be a logging level, if not valid the error level is used

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Parameters:
Name Type Attributes Description
level string

logging level, can be one of the default levels or custom one registered with {registerLevel}
args ...any <repeatable>

arguments to log

(static) none(…args)

Description:

  • Log with NONE level, no-op

Source:
Parameters:
Name Type Attributes Description
args ...any <repeatable>

(static) registerLevel(level, callback, optionsopt)

Description:

  • Register a custom level handler, must be invoked via logger.logger only, if no handler registered for given level the whole message will be logger as an error. The custom handler is called in the context of the module which means the options are available inside the handler.

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Parameters:
Name Type Attributes Description
level string

custom log level
callback function()

call it for this level
options Object <optional>

(static) setDebugFilter(label, {function)

Description:

  • Enable debugging level for this label, if used with the same debugging level it will be printed regardless of the global level, a label is first argument to the logger.debug methods, it is used as is, usually the fist argument is the current function name with comma, like logger.debug("select:", name, args)

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Parameters:
Name Type Description
label string

label(s) to debug, can be a comma separated list
{function

handler - can be a function to be used instead of regular logging, this is for rerouting some output to a custom console or for dumping the actual Javascript data without preformatting, most useful to use console.log

(static) setFile(file)

Description:

  • Redirect logging into a file, disables syslog

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Parameters:
Name Type Description
file string
Example
logger.setFile('var/log/error.log')

(static) setInspect(inspect, inspectArgsopt)

Description:

  • Install a custom inspector with options

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Parameters:
Name Type Attributes Description
inspect function()

function to output
inspectArgs object <optional>

(static) setLevel(level)

Description:

  • Set the output level, it can be a number or one of the supported level names, on invalid level then WARN is set

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Parameters:
Name Type Description
level stream

(static) setOptions(options)

Description:

  • Special options for logger to override defaults, syslog options must start with syslog- For tag, date, pid values may refer to other env variables if start with $, like BKJS_LOG_TAG='$BKJS_TAG'

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Parameters:
Name Type Description
options Object
Properties
Name Type Attributes Description
filter string <optional>

debug filters
level string <optional>

set current level
tag string <optional>

syslog tag
pid int <optional>

process id
date date <optional>

date format: local, iso, utc
oneline boolean <optional>

replace newlines if true
json boolean <optional>

enable JSON mode, each entry will be an Array
syslog-hostname string <optional>

syslog hostname to use
syslog-facility string <optional>

syslog hostname to use
syslog-bsd boolean <optional>

syslog version
syslog-rfc5424 boolean <optional>

syslog version
syslog-rfc3164 boolean <optional>

syslog version

(static) setSyslog(facility)

Description:

  • Enable or close syslog mode

Source:
Parameters:
Name Type Description
facility int | string

syslog facility as a number or remote syslog server:, nullish value will disable syslog
Example
logger.setSyslog('unix://')
logger.setSyslog('udp://host?tag=app')
logger.setSyslog('tcp://host:514?facility=LOG_LOCAL0')

// Back to console output
logger.setSyslog()

(static) trace()

Description:

  • Print stack backtrace as error

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(static) warn(…args)

Description:

  • Log with WARN level

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Parameters:
Name Type Attributes Description
args ...any <repeatable>