Vorpal - Log

A Vorpal.js extension adding simple logging methods.

Installation

npm install vorpal-log
npm install vorpal

Getting Started

const vorpal = (require('vorpal'))();
const vorpalLog = require('vorpal-log');

vorpal.use(vorpalLog)
  .delimiter('vorpal-log demo $')
  .show();

const logger = vorpal.logger;

vorpal.command('log')
  .action(function(args, cb) {
  logger.debug('Log command called without arguments.');
  logger.log('Foo, bar, baz!');
  logger.confirm('You successfully ran the log command.');
  logger.info('It logs stuff.');
  logger.warn('Careful with that axe, Eugene!');
  logger.error('Something went wrong...');
  logger.fatal('If this was a real program, it would probably shut down now.');
  cb();
});

logger.info('This is a demo program for the vorpal-log extension.');
logger.info('Run log to produce some output.');
logger.info('Run loglevel <level> to change the level, e.g. \'loglevel warn\'');

Default Functionality

Vorpal-log comes with the following predefined methods for logging:

logger.debug(msg) (loglevel 10)
logger.log(msg) (loglevel 20)
logger.info(msg) (loglevel 20)
logger.confirm(msg) (loglevel 20)
logger.warn(msg) (loglevel 30)
logger.error(msg) (loglevel 40)
logger.fatal(msg) (loglevel 50)

logger.printMsg(msg) will always print the message without caring about the loglevel or formatting.

Set the loglevel:

logger.setFilter(level)

E.g. logger.setFilter('warn') will only print messages via logger.warn, logger.error and logger.fatal.

Options

The following options passed by vorpal.use(vorpalLogger, options) are used:

printDate: If this is true, the default formatters begin each message with the current date.
preformat: a function which is passed the message and which returns a string which should be logged instead by the default formatters. Could for example be used to render marked.

Commands

Vorpal-log adds the following (hidden) command, which simply delegates to logger.setFilter. As a user can enable debug logging with it, you might want to remove it for production.

Usage: loglevel [options] <level>


set the log level

Options:

  --help  output usage information

Customizing

logger.addFormatter(name, level, format)

Creates a logger[name] function, which will log the result of format(msg) with loglevel level. Use this to add custom formatters.

See customFormatter here for a working, insightful and useful example.

logger.setFilter(filter)

Takes either a custom filter function, a string, or a number.

When logging something, the formatter is passed to the function set by logger.setFilter. Logging only happens if this function returns true.

If logger.setFilter is passed a function, this function is the new filter function.

If passed a number, the new filter function will only log, if formatter.level is greater than or equal to that number.

If passed a string, the new filter function will only log if formatter.level is greater than or equal to formatters[filter].level.

AljoschaMeyer/vorpal-log