electron-log

Description

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>/log.log
• on macOS: ~/Library/Logs/<app name>/log.log
• on Windows: %USERPROFILE%\AppData\Roaming\<app name>\log.log

Documentation on this page is for v3.0.0 beta version, which will be released in January. Documentation for v2.2.17 is here and here is a migration guide.

Installation

Install with npm:

npm install electron-log

Install v3 beta version:

npm install electron-log@beta

Usage

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

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

Log levels

electron-log supports the following log levels:

error, warn, info, verbose, debug, silly

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.clear();

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'

File transport

The file transport writes log messages to a file.

Options

• fileName, default 'log.log'
• format, default '[{y}-{m}-{d} {h}:{i}:{s}.{ms}] [{level}] {text}'
• level, default 'silly'
• maxSize of log file in bytes, 1048576 (1mb) by default.

Detailed description of file transport options and methods.

Renderer console transport

When logging inside main process, it shows log in DevTools console too. This transport can impact on performance, so it's disabled by default for packaged application.

Main console transport

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

Remote transport

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

Options

• level, default false
• url

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: ILogMessage) => void, so you can easily override/add your own transport. More info.

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 = {});

Options

• showDialog, default true for the main process. Set it to false to prevent showing a default electron error dialog
• onError, (error) => void, default null - attach a custom error handler

Hooks

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

(msg: ILogMessage, transport: ITransport) => ILogMessage

More info.

License

Licensed under MIT.