electron-log v5.1.7
electron-log
Simple logging module Electron/Node.js/NW.js application. No dependencies. No complicated configuration.
By default, it writes logs to the following locations:
- on Linux:
~/.config/{app name}/logs/main.log
- on macOS:
~/Library/Logs/{app name}/main.log
- on Windows:
%USERPROFILE%\AppData\Roaming\{app name}\logs\main.log
Installation
Starts from v5, electron-log requires Electron 13+ or Node.js 14+. Feel free to use electron-log v4 for older runtime. v4 supports Node.js 0.10+ and almost any Electron build.
Install with npm:
npm install electron-log
Usage
Main process
import log from 'electron-log/main';
// Optional, initialize the logger for any renderer process
log.initialize();
log.info('Log from the main process');
Renderer process
If a bundler is used, you can just import the module:
import log from 'electron-log/renderer';
log.info('Log from the renderer process');
This function uses sessions to inject a preload script to make the logger available in a renderer process.
Without a bundler, you can use a global variable __electronLog
. It contains
only log functions like info
, warn
and so on.
There are a few other ways how a logger can be initialized for a renderer process. Read more.
Node.js and NW.js
import log from 'electron-log/node';
log.info('Log from the nw.js or node.js');
electron-log v2.x, v3.x, v4.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
Transport
Transport is a simple function which does some work with log message. By default, two transports are active: console and file.
You can set transport options or use methods using:
log.transports.console.format = '{h}:{i}:{s} {text}';
log.transports.file.getFile();
Each transport has level
and
transforms
options.
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, force enable/disable styles
Read more about console transport.
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'
resolvePathFn function sets the log path, for example
log.transports.file.resolvePathFn = () => path.join(APP_DATA, 'logs/main.log');
Read more about file transport.
IPC transport
It displays log messages from main process in the renderer's DevTools console.
By default, it's disabled for a production build. You can enable in the
production mode by setting the level
property.
Options
- level, default 'silly' in the dev mode,
false
in the production.
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.
Third-party transports
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.errorHandler.startCatching(options?)
;
Electron events logging
Sometimes it's helpful to save critical electron events to the log file.
log.eventLogger.startLogging(options?)
;
By default, it save the following events:
certificate-error
,child-process-gone
,render-process-gone
ofapp
crashed
,gpu-process-crashed
ofwebContents
did-fail-load
,did-fail-provisional-load
,plugin-crashed
,preload-error
of every WebContents. You can switch any event on/off.
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, transportName) => LogMessage
Multiple logger instances
You can create multiple logger instances with different settings:
import log from 'electron-log/main';
const anotherLogger = log.create({ logId: 'anotherInstance' });
Be aware that you need to configure each instance (e.g. log file path) separately.
Logging scopes
import log from 'electron-log/main';
const userLog = log.scope('user');
userLog.info('message with user scope');
// Prints 12:12:21.962 (user) › message with user scope
By default, scope labels are padded in logs. To disable it, setlog.scope.labelPadding = false
.
Related
- electron-cfg - Settings for your Electron application.
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