electron-log

Description

Just a simple logging module for your Electron or NW.js application. No dependencies. No complicated configuration. Just require and use. It can be used without Electron.

By default it writes logs to the following locations:

• on Linux: ~/.config/<app name>/log.log
• on OS X: ~/Library/Logs/<app name>/log.log
• on Windows: %USERPROFILE%\AppData\Roaming\<app name>\log.log

Installation

Install with npm:

npm install electron-log

Usage

var log = require('electron-log');

log.info('Hello, log');

If you would like to use electron-log in a renderer process only, you should require it in the main process too.

Log levels

electron-log supports the following log levels:

error, warn, info, verbose, debug, silly

Transport

Transport is a simple function which requires an object which describes a message. By default, two transports are active: console and file.

Please be aware that the file log level is 'warn' by default, so info and debug messages won't be written to a log file.

The file path is dependent on the current platform.

Transport config is available only inside the main process.

Disable default transport:

log.transports.file.level = false;
log.transports.console.level = false;

Override transport:

var format = require('util');

log.transports.console = function(msg) {
  var text = util.format.apply(util, msg.data);
  console.log(`[${msg.date.toLocaleTimeString()} ${msg.level}] ${text}`);
};

Please be aware that if you override a transport function the default transport options (like level or format) will be undefined.

Console Transport

// Log level
log.transports.console.level = 'warn';

/**
 * Set output format template. Available variables:
 * Main: {level}, {text}
 * Date: {y},{m},{d},{h},{i},{s},{ms},{z}
 */
log.transports.console.format = '{h}:{i}:{s}:{ms} {text}';

// Set a function which formats output
log.transports.console.format = (msg) => util.format.apply(util, msg.data);

Renderer Console transport

Show logs in Chromium DevTools Console. It has the same options as console transport.

File transport

// Same as for console transport
log.transports.file.level = 'warn';
log.transports.file.format = '{h}:{i}:{s}:{ms} {text}';

// Set approximate maximum log size in bytes. When it exceeds,
// the archived log will be saved as the log.old.log file
log.transports.file.maxSize = 5 * 1024 * 1024;

// Set maximum log files count. When it exceeds,
// oldest old log file is deleted.
log.transports.file.maxItems = 4;

// Set timestamp format postfixed to log file.
log.transports.file.timeStampPostfixFormat = '{y}{m}{d}{h}{i}{s}';

// Write to this file, must be set before first logging
log.transports.file.file = __dirname + '/log.txt';

// fs.createWriteStream options, must be set before first logging
// you can find more information at
// https://nodejs.org/api/fs.html#fs_fs_createwritestream_path_options
log.transports.file.streamConfig = { flags: 'w' };

// set existed file stream
log.transports.file.stream = fs.createWriteStream('log.txt');

By default, file transport reads a productName or name property from package.json to determine a log path like ~/.config/<app name>/log.log. If you have no package.json or you want to specify another path, just set the appName property:

log.transports.file.appName = 'test';

This value should be set before the first log method call.

Renderer process

Since version 2.0.0 this package works differently in main and renderer processes. When it's included in a renderer process it sends logs to the main process through IPC. There are no API changes, you can still require the package by the same way both in main and renderer processes, but please be aware that transport configuration is available only inside the main process.

Change Log

2.2.20

• Fixed file and folder path handling part using path pacakge.

2.2.19

• Enabled log file rotation. By default log file is archived with datetimestamp postfixed to the log file name when max size limit is reached. When total number of files including active and archived log files is exceeded transports.file.maxItems, oldest old log file is deleted and this is repeated.
• Enabled configuring datetimestamp postfix format attached to archived log file by using transports.file.timeStampPostfixFormat. Here datetimestamp values are all refering UTC time values.

2.2.18

• Fixed a limitation of log file naming + log rotation feature. Before it was not possible to have any other file extension than .log for the log rotation feature to work. Now it's possible to use any file extension.

2.1.0

• Add Renderer Console transport

2.0.0

• Move log.appName property to log.transports.file.appName.
• Change a log message object. See updated Override transport section if you use a custom transport.
• Now it's not possible to configure transports from a renderer process, only from the main.
• To disable a transport set its level to false.
• Fix problems when this package is used from a renderer process.
• Add Typescript definitions.
• Add log-s transport (experimental).
• Fix file transport appName detection when an application is run in dev environment (through electron . or similar way)

1.3.0

• #18 Rename 'warning' log level to 'warn'

1.2.0

• #14 Use native console levels instead of console.log

1.0.16

• Prefer to use package.json:productName instead of package.json:name to determine a log path.

License

Licensed under MIT.