Logzen is a simple and flexible logging library for Javascript that provides easy-to-use logging functionality with customizable log levels and the ability to output logs to different streams and consoles.
You can install Logzen using npm:
npm install logzenTo use Logzen in your project, you need to import the Logger class from the Logzen package:
import { Logger } from 'logzen';Create a new Logger instance to start logging:
const logger = new Logger();
logger.log('This is a log message.');
logger.warn('This is a warning message.');
logger.error('This is an error message.');
logger.debug('This is a debug message.');You can customize the log levels by setting the attachGlobalConsole option to false and manually attaching the console with custom log levels:
import { Logger, LogLevel } from 'logzen';
const logger = new Logger({ attachGlobalConsole: false });
// Attach console with custom log levels
logger.attach(console, LogLevel.WARN, LogLevel.ERROR);
logger.error('This message will be sent to the console.');
logger.log('This message will not be sent to the console!');Logzen supports logging to files by attaching file streams to the Logger instance. This allows you to send log entries with specific log levels to separate log files.
import { Logger, LogLevel } from 'logzen';
import fs from 'fs';
// Create a writable stream to a log file
const logFileStream = fs.createWriteStream('app.log', { flags: 'a' });
const errorFileStream = fs.createWriteStream('error.log', { flags: 'a' });
// Create the Logger instance
const logger = new Logger({ attachGlobalConsole: false });
// Attach the file stream with specific log levels
logger.attach(logFileStream, LogLevel.LOG, LogLevel.INFO);
logger.attach(errorFileStream, LogLevel.WARN, LogLevel.ERROR);
logger.log('This log message will be written to the app.log file.');
logger.error('This error message will also be written to the error.log file.');You can detach streams and consoles from the Logger using the detachStream and detachConsole methods:
const logger = new Logger();
// Detach streams and Console objects
logger.detach(stream, LogLevel.LOG, LogLevel.WARN);
logger.detach(console);You can also attach Console objects to the Logger instance to output logs to the console. This is useful if you have multiple consoles and want to output to all of them.
const logger = new Logger({ attachGlobalConsole: false });
logger.attach(console, LogLevel.WARN, LogLevel.ERROR);
logger.log('This log message will be not sent to the console.');
logger.error('This error will be sent to the console!');By default, logs are retained in memory. You can disable log retention by setting the retainLogs option to false. Note that if you disable log retention, calling a Logger's toString method will return an empty string.
const logger = new Logger({ retainLogs: false });
logger.log('This log message will not be retained in memory.');
logger.warn('This warning message will also not be retained.');When attaching a stream or console without specifying log levels, all will be attached. Likewise, when detaching, the stream or console will be completly removed.
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