Add Support for Cascading LogLevel Configuration

[jonnyreeves]

JSLogger should cascade the LogLevel configuration for named loggers based on their namespace, so for example:

var loggerA = Logger.get("parentNS.clientA");

// Configure the LogLevel of the parent namespace
Logger.get("parentNS").setLevel(Logger.WARN);

loggerA.info("Info Message"); // No output
loggerA.warn("Warning Message"): // Logs "Warning Message"

This feature would provide developers a way to express log levels for an entire group of clients without having to manually list them all out.

[Download]

You could have a look at how debug does this.

Debug has no global logger, only named loggers. And it is basically just a list, there is no hierarchy.
But it can simulate hierarchy through naming conventions. They recommend using colon : to separate levels:

var debug = require('debug')
var log = require('my-app:my-module')
log('Hello!')

By default, this would not produce any output, but you can enable loggers using a pattern:

debug.enable('my-app:my-module') // enables only the one module
debug.enable('my-app:*') // enables every submodule of my-app

They translate the pattern and then use simple regex pattern matching on the name to determine if the logger is enabled or not. It works surprisingly well.