electron-log

What is electron-log?

The electron-log package is a logging library specifically designed for Electron applications. It allows you to log messages to various outputs such as the console, files, and remote servers. It is highly configurable and supports different log levels, making it a versatile tool for debugging and monitoring Electron apps.

What are electron-log's main functionalities?

Console Logging

Logs messages to the console. This is useful for debugging during development.

const log = require('electron-log');
log.info('Hello, console!');

File Logging

Logs messages to a file. This is useful for keeping a persistent log that can be reviewed later.

const log = require('electron-log');
log.transports.file.file = '/path/to/log.txt';
log.info('Hello, file!');

Remote Logging

Logs messages to a remote server. This is useful for centralized logging and monitoring.

const log = require('electron-log');
log.transports.remote.url = 'https://your-log-server.com/log';
log.info('Hello, remote server!');

Custom Transports

Allows you to define custom transports for logging. This is useful for extending the logging functionality to meet specific needs.

const log = require('electron-log');
log.transports.custom = (msg) => {
  // Custom transport logic
  console.log('Custom transport:', msg);
};
log.info('Hello, custom transport!');

Log Levels

Supports different log levels (error, warn, info, verbose, debug, silly). This is useful for controlling the verbosity of the logs.

const log = require('electron-log');
log.level = 'warn';
log.info('This will not be logged');
log.warn('This will be logged');

Other packages similar to electron-log

winston

Winston is a versatile logging library for Node.js that supports multiple transports, log levels, and formats. It is highly configurable and can be used in a variety of applications, not just Electron.

bunyan

Bunyan is a simple and fast JSON logging library for Node.js. It is designed for high-performance logging and supports various transports and log levels. It is particularly useful for applications that require structured logging.

log4js

Log4js is a logging library inspired by the Java log4j library. It supports multiple appenders (transports), log levels, and configurations. It is a mature and widely-used library in the Node.js ecosystem.

README

electron-log

Just a simple logging module for your Electron or NW.js application. No dependencies. No complicated configuration. Just require and use. Also, it can be used without Electron in any node.js application.

By default, it writes logs to the following locations:

• on Linux: ~/.config/{app name}/logs/{process type}.log
• on macOS: ~/Library/Logs/{app name}/{process type}.log
• on Windows: %USERPROFILE%\AppData\Roaming\{app name}\logs\{process type}.log

Installation

Install with npm:

npm install electron-log

Usage

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

log.info('Hello, log');
log.warn('Some problem appears');

electron-log v2.x, v3.x

If you would like to upgrade to the latest version, read the migration guide and the changelog.

Log levels

electron-log supports the following log levels:

error, warn, info, verbose, debug, silly

nodeIntegration

If you've got an error like require is not defined in a renderer process, read the nodeIntegration section.

Transport

Transport is a simple function which does some work with log message. By default, two transports are active: console and file.

If you change some transport options, make sure you apply the changes both in main and renderer processes.

You can set transport options or use methods using:

log.transports.console.format = '{h}:{i}:{s} {text}';

log.transports.file.getFile();

Console transport

Just prints a log message to application console (main process) or to DevTools console (renderer process).

Options

• format, default '%c{h}:{i}:{s}.{ms}%c › {text}' (main), '{h}:{i}:{s}.{ms} › {text}' (renderer)
• level, default 'silly'
• useStyles, use styles in the main process even if TTY isn't attached, default null

File transport

The file transport writes log messages to a file.

Options

• format, default '[{y}-{m}-{d} {h}:{i}:{s}.{ms}] [{level}] {text}'
• level, default 'silly'
• resolvePath function sets the log path, for example

log.transports.file.resolvePath = () => path.join(APP_DATA, 'logs/main.log');

Read more about file transport.

IPC transport

When logging inside renderer process, it also shows log in application console and vice versa. This transport can impact on performance, so it's disabled by default for packaged application.

If you don't use electron-log in the main process but want to show renderer logs in the console, add require('electron-log') somewhere in the main code.

Options

• level, default 'silly'

Remote transport

Sends a JSON POST request with LogMessage in the body to the specified url.

Options

• level, default false
• url, remote endpoint

Read more about remote transport.

Disable a transport

Just set level property to false, for example:

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

Override/add a custom transport

Transport is just a function (msg: LogMessage) => void, so you can easily override/add your own transport. More info.

Overriding console.log

Sometimes it's helpful to use electron-log instead of default console. It's pretty easy:

console.log = log.log;

If you would like to override other functions like error, warn and so on:

Object.assign(console, log.functions);

Colors

Colors can be used for both main and DevTools console.

log.info('%cRed text. %cGreen text', 'color: red', 'color: green')

Available colors:

• unset (reset to default color)
• black
• red
• green
• yellow
• blue
• magenta
• cyan
• white

For DevTools console you can use other CSS properties.

Catch errors

electron-log can catch and log unhandled errors/rejected promises:

log.catchErrors(options?);

More info.

Hooks

In some situations, you may want to get more control over logging. Hook is a function which is called on each transport call.

(message: LogMessage, transport: Transport) => LogMessage

More info.

Multiple logger instances

You can create multiple logger instances with different settings:

const electronLog = require('electron-log');

const log = electronLog.create('anotherInstance');

Logging scopes

const log = require('electron-log');
const userLog = log.scope('user');

userLog.info('message with user scope');
// Prints 12:12:21.962 (user) › message with user scope

Web Worker

It's possible to use the module with Web Worker. However, ipc transport is not active, so log messages from worker are not displayed in the main app console.

Related

• electron-cfg - Settings for your Electron application.