deno-logger

logger for deno

Logger interface

interface fileLoggerOptions {
  rotate?: boolean;  // cut by day
  now?: boolean; // print datetime or not
  maxBytes?: number, // the maximum size in bytes that the log file can grow to before rolling over to a new one
  maxBackupCount?: number // maxBackupCount must work with maxBytes
}

interface LoggerInerface {
  constructor() {}

  info(...args: unknown[]): void
  warn(...args: unknown[]): void
  error(...args: unknown[]): void

  async initFileLogger(dir: string, options: fileLoggerOptions = {}): Promise<void>

  disableConsole(): void
  enableConsole(): void

  disableFile(): void;
  enableFile(): void;

  disable(): void;
  enable(): void;
}

Useage

console logger

import Logger from "https://deno.land/x/logger@v1.0.0/logger.ts";

const logger = new Logger();

logger.info('i am from consoleLogger', { name: 'zfx' });
logger.warn('i am from consoleLogger', 1, 'any');
logger.error('i am from consoleLogger', new Error('test'));

file and console logger

import Logger from "https://deno.land/x/logger@v1.0.0/logger.ts";

const logger = new Logger();

// console only
logger.info('i am from consoleLogger', { name: 'zfx' });
logger.warn('i am from consoleLogger', 1, 'any');
logger.error('i am from consoleLogger', new Error('test'));

await logger.initFileLogger('../log');

// file and console
logger.info('i am from fileLogger', { name: 'zfx' });
logger.warn('i am from fileLogger', 1, 'any');
logger.error('i am from fileLogger', new Error('test'));

file logger only

import Logger from "https://deno.land/x/logger@v1.0.0/logger.ts";

const logger = new Logger();
await logger.initFileLogger('../log');
logger.disableConsole();

// file only
logger.info(['i am from fileLogger', 1], { name: 'zfx' });

file logger optional parameter

interface

interface fileLoggerOptions {
  rotate?: boolean,  // cut by day
  maxBytes?: number; 
  // Only available if maxBytes is provided, Otherwise you will get an error
  maxBackupCount?: number; 
}

example

import Logger from "https://deno.land/x/logger@v1.0.0/logger.ts";
const logger = new Logger();

// cut by day
// filename is [date]_[type].log
// example 2020-05-25_warn.log, 2020-05-25_info.log, 2020-05-25_error.log
await logger.initFileLogger('../log', {
  rotate: true
});

// maxBytes
// filename is [type].log.[timestamp]
// example: info.log.1590374415956
await logger.initFileLogger('../log', {
  maxBytes: 10 * 1024
});

// rotate and maxBytes
// filename is [date]_[type].log.[timestamp]
// example: 2020-05-25_info.log.1590374415956
await logger.initFileLogger('../log', {
  rotate: true, 
  maxBytes: 10 * 1024
});

// maxBytes and maxBackupCount
// filename is [type].log.[n] 
// example info.log.1, info.log.2 ...
// when reach maxBackupCount, the [type].log.[maxBackupCount-1] will be overwrite
/* 
 detail: 
`maxBytes` specifies the maximum size
in bytes that the log file can grow to before rolling over to a new one. If the
size of the new log message plus the current log file size exceeds `maxBytes`
then a roll over is triggered. When a roll over occurs, before the log message
is written, the log file is renamed and appended with `.1`. If a `.1` version
already existed, it would have been renamed `.2` first and so on. The maximum
number of log files to keep is specified by `maxBackupCount`. After the renames
are complete the log message is written to the original, now blank, file.

Example: Given `log.txt`, `log.txt.1`, `log.txt.2` and `log.txt.3`, a
`maxBackupCount` of 3 and a new log message which would cause `log.txt` to
exceed `maxBytes`, then `log.txt.2` would be renamed to `log.txt.3` (thereby
discarding the original contents of `log.txt.3` since 3 is the maximum number of
backups to keep), `log.txt.1` would be renamed to `log.txt.2`, `log.txt` would
be renamed to `log.txt.1` and finally `log.txt` would be created from scratch
where the new log message would be written.
*/
await logger.initFileLogger('../log', {
  maxBytes: 10 * 1024, 
  maxBackupCount: 10  
});

// rotate and maxBytes and maxBackupCount
// filename is [date]_[type].log.[n]
// example 2020-05-25_info.log.1, 2020-05-25_info.log.2
// when reach maxBackupCount, the [type].log.[maxBackupCount-1] will be overwrite
await logger.initFileLogger('../log', {
  rotate: true,  
  maxBytes: 10 * 1024, 
  maxBackupCount: 10 
});

// rotate and maxBackupCount
// maxBackupCount will be ignored
await logger.initFileLogger('../log', {
  rotate: true,  
  maxBackupCount: 10 
});

The following conditions will throw an error

// maxBackupCount
// get error => maxBackupCount must work with maxBytes
await logger.initFileLogger('../log', {
  maxBackupCount: 10 
});
// rotate and maxBackupCount
// get error => maxBackupCount must work with maxBytes
await logger.initFileLogger('../log', {
  rotate: true,
  maxBackupCount: 10 
});

disableConsole and enableConsole

import Logger from "https://deno.land/x/logger@v1.0.0/logger.ts";

const logger = new Logger();

// console
logger.info('console enabled, you can see me');
logger.disableConsole();
// no message is logged
logger.info('console disabled');
logger.enableConsole();
// console
logger.info('console enabled, you can see me');

disableFile and enableFile

import Logger from "https://deno.land/x/logger@v1.0.0/logger.ts";

const logger = new Logger();
await logger.initFileLogger('../log');

logger.disableFile();
// not log to file
logger.info('file disbaled');
logger.enableFile();
// log to file
logger.info('file enabled, you can see me');

disable and enable

• disable disable write to file and terminal, don't care if it is currently writing to a file or terminal, but hope to restore the currently configuration later
• enable restore previous log configuration: file, terminal or both

example:

1. fileLogger => disable => enable => fileLogger
2. consoleLogger => disable => enable => consoleLogger
3. fileLogger, consoleLogger => disable => enable => fileLogger, consoleLogger

import Logger from "https://deno.land/x/logger@v1.0.0/logger.ts";

const logger = new Logger();
await logger.initFileLogger('../log');

logger.disable();
logger.enable();

test

deno test --allow-read --allow-write

Screenshots

consoleLogger

fileLogger

cut logs by day

More screenshots in the screenshots folder.