Adjusting Log Levels Globally

While certain transports and logging libraries may allow you to adjust log levels at an individual level, you can adjust log levels in LogLayer globally across all transports.

Global vs Transport Log Levels

The log level methods described here set the global log level for LogLayer. However, individual transports and logging libraries may have their own log level settings that also apply. When both are set, the most restrictive level takes effect.

For example, if LogLayer's global level is set to debug, but a transport or logging library has its level set to error, the transport will only send out error and fatal messages, even though the global level allows debug messages.

Log Level Hierarchy

Log levels follow a hierarchy, with lower numeric values indicating higher priority:

Level	Value
trace	60
debug	50
info	40
warn	30
error	20
fatal	10

For example, when using setLevel(), all levels equal to and below it are also enabled.

For example, if you set the log level to warn:

• higher levels info, debug, and trace messages will be ignored.
• equal and lower levels warn, error, and fatal messages will be logged

Enabling/Disabling Logging

All of these methods can be used during runtime to dynamically adjust log levels without restarting your application. You can control whether logs are output using these methods:

Set Log Level

All levels equal to and below the set level are enabled.

import type { LogLevel } from 'loglayer'

// Enable warn, error, and fatal (disable info, debug, trace)
log.setLevel(LogLevel.warn)

Enable / Disable All Logging

log.disableLogging()

log.enableLogging()

Individual Log Levels

You can ignore the hierarchy by using enableIndividualLevel() and disableIndividualLevel() methods to enable or disable specific log levels.

import type { LogLevel } from 'loglayer'

log.enableIndividualLevel(LogLevel.debug)  // Enable only debug logs

import type { LogLevel } from 'loglayer'

log.disableIndividualLevel(LogLevel.debug) // Disable only debug logs

Checking if a Log Level is Enabled

You can check if a specific log level is enabled using the isLevelEnabled method:

import type { LogLevel } from 'loglayer'

if (log.isLevelEnabled(LogLevel.debug)) {
  log.debug('Debugging is enabled')
} else {
  log.info('Debugging is disabled')
}

Log Level Managers

New in LogLayer v8.

Log level managers control how log levels are inherited and propagated between parent and child loggers. By default, LogLayer uses the Default Log Level Manager, which provides independent log level management for each logger instance.

With the default log level manager, child loggers inherit the log level from their parent when created, but subsequent changes to the parent's log level do not affect existing children:

import { LogLayer, ConsoleTransport, LogLevel } from "loglayer";

const parentLog = new LogLayer({
  transport: new ConsoleTransport({ logger: console })
});

parentLog.setLevel(LogLevel.warn);
const childLog = parentLog.child();

// Child inherits parent's log level at creation
childLog.isLevelEnabled(LogLevel.warn); // true
childLog.isLevelEnabled(LogLevel.info); // false

// Parent change does not affect child
parentLog.setLevel(LogLevel.debug);
childLog.isLevelEnabled(LogLevel.debug); // false (child not affected)

For more information about log level managers and available options, see the Log Level Managers documentation.