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Easylogging++ Node.js Binding

Easylogging++ Node.js binding provides ability to use efficient Easylogging++ to log important logs for your application.

Requirements

• Node 7+

Download

npm install --save easyloggingpp

Getting Started

const easyloggingpp = require('easyloggingpp');
const ConfigType = easyloggingpp.ConfigType;
const Level = easyloggingpp.Level;
const logger = easyloggingpp.getLogger('mylogger'); // register logger

easyloggingpp.configureAllLoggers([
    {
        config: ConfigType.Format,
        value: '%levshort %datetime %fbase:%line %msg',  // <-- fbase or file for full path
    },
    {
        config: ConfigType.Filename,
        value: 'logs/output.log'
    }
]);

// alternatively you can use following to set default configurations
// for future loggers as well as existing logger
easyloggingpp.configureAllLoggers({
    config_file: 'easylogging-config.conf',
});

logger.info('simple log');
logger.info('array %s', [1, 2, 3]);
var person = { 'name': 'Adam', 'age': 960, }
logger.info('obj %s', person);

logger.error('an error occurred %s', new Error("error msg"));

easyloggingpp.setLogErrorStack(false); // turn stack logging off
logger.fatal('serious error occurred %s', new Error("fatal msg"));
logger.error('an error occurred %s', new Error("error msg"));

Above will print something like:

Log

logger.info(...);
logger.warn(...);
logger.error(...);
logger.debug(...);
logger.trace(...);
logger.fatal(...);
logger.verbose(verbose_level, ...);

Log Formats

You can use advanced logging format specifiers.

logger.info('array %s', [1, 2, 3]);

Taken from utils.format

Format specifier	Explanation
%s	String.
%d	Number (integer or floating point value).
%i	Integer.
%f	Floating point value.
%j	JSON. Replaced with the string '[Circular]' if the argument contains circular references.
%%	single percent sign ('%'). This does not consume an argument.

%o and %O should not be used. Use %s instead for better output.

Global Configuration

via File

easyloggingpp.configureAllLoggers({
    config_file: 'easylogging-config.conf',
});

This will configure all the existing loggers and set this new configuation to default for future loggers.

All Levels

easyloggingpp.configureAllLoggers({
    config: easyloggingpp.ConfigType.Format,
    value: '%datetime %msg',
});

or using array

easyloggingpp.configureAllLoggers([
  {
      config: easyloggingpp.ConfigType.Format,
      value: '%datetime %msg',
  },
  {
    config: easyloggingpp.ConfigType.Format,
    value: '%datetime %file:%line %msg',
  }
]);

This will configure existing loggers but will not change future loggers.

Specific Level

easyloggingpp.configureAllLoggers({
    level: easyloggingpp.Level.Info,
    config: easyloggingpp.ConfigType.Format,
    value: '%datetime %msg',
});

or using array

easyloggingpp.configureAllLoggers([
  {
      level: easyloggingpp.Level.Info,
      config: easyloggingpp.ConfigType.Format,
      value: '%datetime %msg',
  },
  {
    level: easyloggingpp.Level.Debug,
    config: easyloggingpp.ConfigType.Format,
    value: '%datetime %file:%line %msg',
  }
]);

This will configure existing loggers but will not change future loggers.

Logger Configuration

via File

const logger = easyloggingpp.getLogger('logger1');
logger.configure({
    config_file: 'easylogging-config.conf',
});

All Levels

const logger = easyloggingpp.getLogger('logger1');

logger.configure({
    config: easyloggingpp.ConfigType.Format,
    value: '%datetime %msg',
});

or using array

const logger = easyloggingpp.getLogger('logger1');
logger.configure({
    config: easyloggingpp.ConfigType.Format,
    value: '%datetime %msg',
});

Specific Level

const logger = easyloggingpp.getLogger('logger1');

logger.configure({
    config: easyloggingpp.ConfigType.Format,
    value: '%datetime %msg',
});

or using array

const logger = easyloggingpp.getLogger('logger1');
logger.configure({
    config: easyloggingpp.ConfigType.Format,
    value: '%datetime %msg',
});

This will configure existing loggers but will not change future loggers.

Add/Remove Logging Flag

easyloggingpp.addFlag(easyloggingpp.LoggingFlag.ColoredTerminalOutput);
easyloggingpp.removeFlag(easyloggingpp.LoggingFlag.ColoredTerminalOutput);

Profiler

You can use built-in profiler

logger.startProfiling('profiling-id');
// some heavy task
for (var i = 0; i < 100000; ++i) {

}
logger.endProfiling('profiling-id');

// other tasks that will not be profiled
// if needed or you could use finishProfiling directly

logger.finishProfiling('profiling-id', (item) => {
    logger.info(`finished profiling in ${item.diff}ms`);
});

Notes

Some notes for those who have previous experience with Easylogging++ (and for those who are absolutely new)

• Logs are written to /dev/null by default. You must configure via easyloggingpp.configureAllLoggers at initialization.
• Loggers are created automatically when you use easyloggingpp.getLogger.
• ColoredTerminalOutput flag is set by default. You can unset it using easyloggingpp.removeFlag
• You can safely log with Fatal level as DisableApplicationAbortOnFatalLog flag is set by default. You should not remove this flag. Read more

License

Copyright 2017-present Zuhd Web Services
Copyright 2017-present @abumusamq

https://github.com/zuhd-org
https://zuhd.org
https://muflihun.com

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.