A cross-browser logging util

log1.js

/**
 * Cross-browser logging utils
 * 
 * This fn differs from something like the jQuery log plugin in that 
 * it returns console.log, if avail, instead of calling it. This allows 
 * us to call it in file with the log statement, which means that the 
 * line # and file name displayed are more helpful. This isn't supposed 
 * to be a logging framework like blackbird or log4javascript.
 * 
 * Usage: var msg = 'foo'; log(msg).call(console, msg)
 *
 * Requires: jQuery event firing. Swapping in another lib would be trivial
 * 
 * Run this code on JS Bin http://jsbin.com/iyeki4/10
 *
 * @return a noop function if console is undefined
 * @return console.debug or console.log otherwise
 */
var log = function(){

  // Fire event for non-console logging 
  var eventName = 'log';
  $('body').trigger(eventName, arguments);

  // Return noop fn so caller can always call .call() or .apply()
  if(!window.console){
    return function(){};
  }

  // Prefer .debug, which displays file name & line #.
  var logger = console.debug ? console.debug : console.log;

  return logger;
};

module('log util');

// Here's a QUnit test for it
(function(){
  test('log fires event', function(){
    expect(2);
    $(document).delegate('body', 'log', function(e, args){
      ok('foo' === args[0], '1st arg should be foo');
      ok('bar' === args[1], '2nd arg should be bar');
      start();
    });
    var msg = ['foo', 'bar'];
    log(msg).call(console, msg);
    stop();
  });
})();

log2.js

/**
 * Here's another variation on log(), which eliminates the need for 
 * passing in the msg twice. It adds a boilerplate callback, though, 
 * which kinda kills it for me. As above, the goal is to call the 
 * logger in the file containing the log() statement.
 * 
 * Run this on JS Bin http://jsbin.com/upeca3/4
 * 
 */
var log = function(/* args */){

  var eventName = 'log';
  $('body').trigger(eventName, arguments);

  if(!window.console){
    return;
  }

  var args = [].slice.call(arguments, 1);
  var callback = arguments[0];
  var logger = console.debug ? console.debug : console.log;

  callback(console, args, logger);
};

// test
(function(){
  test('log fires event', function(){
    expect(3);
    $(document).delegate('body', 'log', function(){
      ok('bar' === arguments[2], '3rd arg should be bar');
      ok('baz' === arguments[3], '4th arg should be baz');
      ok('bax' === arguments[4], '5th arg should be bax');
      start();
    });
    log(function(c,m,l){l.call(c,m);}, 'bar', 'baz', 'bax');
    stop();
  });
})();