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log4js2

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log4js2

A fast, lightweight (~12KB compressed) JavaScript logger with no runtime dependencies that is designed to mirror Apache Log4j 2 functionality.

0.1.2
Source
npm

Version published: 9 years ago

Weekly downloads: 9; increased by50%

Maintainers: 1

Weekly downloads

Created: 9 years ago

Source

log4js2

A fast, lightweight (~12KB compressed) JavaScript logger with no runtime dependencies that is designed to mirror Apache Log4j 2 functionality.

Setup

Simply require the log4js2 module.

var log4js = require('log4js2');

Or, for HTML implementations, place the log4js distribution in your HTML <head> tag.

<script type="text/javascript" src="log4js2.min.js"></script>

Then, log some stuff!!


// create the logger
var log = log4js.getLogger('myLogger');

// log an event
log.info('This is a log');

// output: "03-24-2016 12:00:18,670|myLogger:anonymous:3|This is a log"

Configuration

Configure log4js using the configure() method. This must be the first thing you do. Otherwise, the first log you commit will not allow updates from this function

log4js.configure({
    tagLayout : '%d{MM-dd-yyyy HH:mm:ss,S}|%logger:%M:%line|%message',
    appenders : [ 'consoleAppender' ],
    loggers : [ {
        logLevel : log4js.LogLevel.INFO
    } ],
    allowAppenderInjection : true
});

Configuration Options

allowAppenderInjection

Type: Boolean Default: false

Turn on or off the ability to inject appenders. If set to false, no appenders can be added after the first log. This may be useful if you need to add an appender during runtime.

appenders

Type: Array.<String> Default: [ 'consoleAppender' ]

Sets the appenders for the given log configuration. Packaged with log4js2 is the console appender. You can develop your own appenders to add more functionality.

loggers

Type: Array.<Object> Default: [{ tag : 'main', logLevel : log4js.LogLevel.INFO }]

Sets the loggers for log4js2. The tag property specifies what logger the appender pertains to (see below), and the logLevel specifies the logging level (use log4js.LogLevel).

log4js.configure({
    // ...
    loggers : [ {
	    logLevel : log4js.LogLevel.INFO
    }, {
		tag : 'debugLogger',
		logLevel : log4js.LogLevel.DEBUG
	} ]
});

var log = log4js.getLogger('myLogger');
var debugLog = log4js.getLogger('debugLogger');

log.debug('This message will not show');
debugLog.debug('This message will show');

tagLayout

Type: String Default: "%d{HH:mm:ss} [%level] %logger - %message"

Sets the tagging layout for the logs. Refer to Apache's Log4j2 documentation for how to set the tag layout. Keep in mind that some of the layout tags are relatively more expensive, and should only really be used in a development environment - such as %method and %line. There are also a few layouts that are not implemented with log4js2:

Callers
Encoders
Equals
Highlight
Marker
Nano Time
Not Empty
Replace
Style
Threads/Thread Context Maps

log4js.configure({
    tagLayout : '%d{MM-dd-yyyy HH:mm:ss,S} [%level] %logger.%M:%line - %message',
    // ...
});

var log = log4js.getLogger('myLogger');
log.warn('This is a log {}', 'with parameters');

// output: 03-24-2016 16:04:41,440 [WARN] myLogger.anonymous:15 - This is a log with parameters

Note: Showing Method Names

In order to make the %method tag word, you must call from named function, like so:

function callerFunction() {
    log.info('This is within a name function');
}
// output: 03-24-2016 16:17:50,360 [INFO] myLogger.callerFunction:3 - This is within a name function

Otherwise, non-named functions will simply display an 'anonymous' placeholder:

var callerFunction = function () {
    log.info('This is an anonymous function');
};
// outputs: 03-24-2016 16:19:42,373 [INFO] myLogger.anonymous:3 - This is an anonymous function

log4js

addAppender(appender)

appender Object

Adds an appender (see configuration). The configuration option allowAppenderInjection must be set to true for this to work.

getLogger(logger)

logger String [optional]

Gets a logger instance. If the logger is not set, the logger name will be pulled from the containing named instance it was created in (anonymous if unnamed).

setLogLevel(logLevel, logger)

logLevel Number (use log4js.LogLevel) logger String [optional]

Sets the log level for a specific logger, or all loggers (if logger is not set).

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Package last updated on 03 May 2016

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