Nn-node-log NPM

Simple Node log

Simple Node log with levels, color, and log location from file name and line number, inspired from the Golang log package.

Caution: This package uses some private APIs from Node, those APIs are not guaranteed to be kept overtime. It's also a new package under heavy developing and has not been well tested yet. If any problem happens, feel free to open an issue.
Require:
- Node >= v8.0.0

Reference

Example

const log = require('nn-node-log')

try {
  process.on('uncaughtException', (err) => {
    log.stack(err)
  })

  // init our express app, router, graphql...

  server.listen(8080, () => log.info('listening on port 8080'))
} catch (err) {
  log.stack(err, 'fatal')
}

Example

API

The exported module is a singleton of lib/Log class. It has the following properties and methods:

`log.level`

string - Default debug
A string to specify the current log level of the instance. It should be one of debug, info, warn, error or fatal.

`log.debugPrefix`

string - Default is an empty string
A string to specify the debug prefix to filter out the unnecessary debug messages.

`log.color`

A boolean flag to indicate that it should print with color or not. Default is true.

`log.skip`

number - Default 3
A number to skip when retrieving the stack trace call layer. We should modify this number when we want to wrap the library inside other function calls.

`log.timezone`

number - Default is the current timezone
A number to specify the target timezone to be printed out.

`log.setCwd(cwd)`

Set the current working directory
Parameters:
- cwd:
  - string - Required

`log.filterFn`

Function - Default from the stacktrace package
A function to filter the stack layer.

`log.filenameFn`

Function - Default from the stacktrace package
A function to get the shortened file name from the stack layer.

`log.debug([f, ...args])`

`log.warn([f, ...args])`

`log.info([f, ...args])`

`log.error([f, ...args])`

`log.fatal([f, ...args])`

Log with a specified format for each level. With fatal level, it will call process.exit(1) to quit the current process afterwards.
Parameters:
- f:
  - string|any - Optional
  - The format pattern. See Node util.format API for detail.
- ...args:
  - any - Optional
  - The rest arguments to be formatted with.

`log.trace(level[, f, ...args])`

Print out together with the call layers.
Parameters:
- level:
  - string - Required
  - A string to specify the level to log.
- f:
  - string|any - Optional
  - The format pattern. See Node util.format API for detail.
- ...args:
  - any - Optional
  - The rest arguments to be formatted with.

`log.stack(err[, level])`

Pretty print out the error.
Parameters:
- err:
  - Error - Required
  - The error to be printed out.
- level:
  - string - Optional - Default error
  - A string to specify the level to log.