ChainedLogger

Hierarchical logging library as close to console as possible. Works in node and the browser.

Log settings are inherited prototypically. If you want to make changes to all loggers not specifying their own logLevel, simply set it at the top level.

debug is provided as a synonym for info.

Basic usage

var log = require("chained-logger");

log.debug("low level detail");
log.log("something interesting");
log.warn("something worrying");
log.error("something really bad!!");

log.info("synonym for debug");

if(process.env.LOG_LEVEL) {
  log.setLogLevel(process.env.LOG_LEVEL);
}

To configure the logging output on a logger, for instance to forward over UDP or disable logging, set log. There is a NULL_CONSOLE` already provided:

var log = require("chained-logger");
log.console = log.NULL_CONSOLE;

Install

Node:

npm install --save chained-logger

Browser:

<script src=chained-logger.js></script>
<script>
// exposed globally as chainedLogger;
</script>

Levels

var log = require("chained-logger");
log.setLogLevel("debug");
log.enabled("debug"); // true

log.setLogLevel("error");
log.enabled("debug"); // false
log.enabled("info"); // false
log.enabled("warn"); // false
log.enabled("log"); // false

The order is DEBUG < LOG < WARN < ERROR.

Inheritence

Log-level and console are inherited from the neartest parent logger with a log-level set. To create a child logger use logger.create().

var log = require("chained-logger");

var child = log.create();
var grandChild = child.create();

log.setLogLevel("error");
child.enabled("warn"); // false
grandChild.enabled("warn"); // false

child.setLogLevel("warn"); 
grandChild.enabled("warn"); // true

Prefixing

It's nice to know where your logs are coming from:

var log = require("chained-logger").create("[server] ");

log.debug("request") // '[server] request'

var put = log.create("[put] ");
put.debug("request") // '[server] [put] request'