module-logger

Logger utility

Installation

npm install

Usage

Log a message

var logger = require("logger")(module);

// Examples.
logger.log("info", "message");
logger.log("info", "message", {anything: "Meta data!"});
logger.info("possible to directly call the level on logger");
logger.warn("Supports %s.", "util.format()'s printf-like interpolation");

The log message will be prepended with the current date and time in the following format: YYYY-MM-DD HH:MM:SS. The timezone will be the local one when in development, UTC otherwise.

The log message will also display between brackets the name of the package inferred from the provided module object, to easily distinguish the emitter.

Note: Any uncaught exception will be caught by the logger, at which point it will display a detailed trace before exiting the application.

Logging levels

The following logging levels, in order of least to most critical, are allowed:

• silly

  Something really really specific, about something already specific. Or something not really noteworthy, in any case. Most of the time it's better to not log it at all, otherwise it would just be silly.

• debug

  Something pretty specific, but useful to have if having elementary problems. Most of the time this will log one iteration of a loop over a collection, for example.

• verbose

  Something rather general about a portion of code, but that allows to understand what is the flow of an application when put together with other verbose calls.

• info

  Something important to know about the application, but that is expected, informative and not negative.

• warn

  Something for which a flag needs to be raised but that is not necessarily critical.

• error

  Something critical that requires immediate attention.

By default the lowest level for which the logs are displayed is info, but that is lowered to verbose in a development environment. If required, the minimum level can be changed by doing the following:

var logger = require("logger")(module);

// Examples.
logger.debug("message"); // Will not display.
logger.setLevel("silly");
logger.debug("message"); // Will display.
logger.setLevel(); // Will revert to the default level for the
                          // original environment.

Keep in mind that multiple modules can be using this module simultaneously and a call to setLevel only affects the logger on which it is applied, use this to your advantage.