multi-level-logger

# Configuration

# Default Configuration

Out-of-the-box Configuration

multi-level-logger is ready out-of-the-box with a default log configured for display at the Warn level.

Default configuration is equal to:

InitializeLogging("warn");
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# Retrieving Configuration

# LogLevels

Member Value
dev 0
trace 10
debug 20
info 30
warn 40
error 50
fatal 60

multi-level-logger exposes the LogLevels enumeration for all named log levels. Levels can be referred to via the string name, the enumeration value, or an integer value between the lowest and highest level.

# GetConfiguredLogging()

Returns: IBaseConfiguration

  • Return the currently configured logging options

# Setting Configuration

# Environment Variable

multi-level-logger supports setting the log level via a LOG_LEVEL environment variable

# Example

const { Info } = require(`multi-level-logger`);

Info("Info-level log");
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> LOG_LEVEL=debug node testLog.js
> 1/1/2018, 12:00:00 PM - [line 3: ./log-example.js] - Info-level log

Note

multi-level-logger defaults to warn, and the log above would not be shown without the use of the enviornment variable

# Methods

# InitializeLogging(logDefinition, logName)

Parameter Required Type Notes
logDefinition yes string | number | ILogDefinition The log level initializer matching one of four types
  1. String - a string matching a log level in the levels object
  2. Number - an integer value to use as the log level
  3. Object - an object with a logLevel property, matching 1 or 2 above
  4. Object - an object with each key matching a named log, and the value as 1, 2, or 3 above
logName no string Name of the log, defaulting to "default"
  • The LogLevels enumeration has number values, and members can be passed directly to logDefinition
# Example
# Set directly

The following sets the default log level to Info, and a log named webserver to Debug

import { InitializeLogging } from "multi-level-logger";

InitializeLogging("info");
InitializeLogging("debug", "webserver");
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# Set via configuration object

This code does exactly the same thing using an object to define multiple logs, and using the LogLevels enumeration

import { LogLevels, InitializeLogging } from "multi-level-logger";

const logDefinition = {
    logLevel: LogLevels.info,
    webserver: { logLevel: LogLevels.debug }
};

InitializeLogging(logDefinition);
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# OutputFormatting(options)

  • Sets the global options for formatting log output
  • Can be overridden per-log-call
Parameter Required Type Notes
options yes ILogOptionConfiguration Set the formatting for output

# Interfaces for Configuration

# IBaseConfiguration

Configuration for the module

Parameter Required Type Notes
includeCodeLocation yes boolean Show the code location when printing to the log
includeTimestamp yes boolean Show a timestamp when printing to the log
jsonFormatter yes number Amount of whitespace to include for the JSON.stringify() function
logLevel yes ILevelConfiguration Minimum log level to display
useColors yes boolean Display colors in a terminal capable of showing them

# ILevelConfiguration

Log level display

Parameter Required Type Notes
default yes number Default log level for all logging

# ILogDefinition

Interface for object used as log initializer

Parameter Required Type Notes
logLevel no string | number Named log level, threshold numerical log value, or log level enumeration
  • Any property in an ILogDefinition that has an Object as it's value which contains a logLevel property will be configured as a named log at that log level

# ILogOptionConfiguration

Log writting configuration for the single message

Parameter Required Type Notes
includeCodeLocation no boolean Show the code location when printing to the log
includeTimestamp no boolean Show a timestamp when printing to the log
jsonFormatter no number Amount of whitespace to include for the JSON.stringify() function
useColors no boolean Display colors in a terminal capable of showing them

← Writing Logs →