Global development and debugging helper (browser)

lawg.js

/**
 * Global development and debugging helper
 * Author: Marc Diethelm
 */

(function() {

	var  w = window
		,c
		,concatArgs
		,initConcatArgs = function() {
		return function concatArgs(args) {
			for (var i = 0, str = ''; i < args.length; i++) {
				if (args[i] !== undefined &&  args[i] !== null)
					str += (args[i].toString() + '  ');
				else
					str += args[i];
			}
			return str;
		}
	};

	if (w.console) {
		c = console;
		if ('dir' in c && 'apply' in c.dir) { // create global shortcuts
			typeof c.log   === 'function' && ( w.log   = function() { c.log.apply(c, arguments) } );
			typeof c.info  === 'function' && ( w.info  = function() { c.info.apply(c, arguments) } );
			typeof c.debug === 'function' && ( w.debug = function() { c.debug.apply(c, arguments) } );
			typeof c.error === 'function' && ( w.error = function() { c.error.apply(c, arguments) } );
			typeof c.dir   === 'function' && ( w.dir   = function() { c.dir.apply(c, arguments) } );
			typeof c.table === 'function' && ( w.table = function() { c.table.apply(c, arguments) } );

			// A tiny jQuery plugin adding logging to any jQuery object
			w.jQuery && (jQuery.fn.log = function(clear) {
				clear && c.clear.call(c);
				c.log.call(c, this);
				return this;
			});
		}
		else { // IE: we have console.log but it just accepts one param. let's fix that! :)
			concatArgs = initConcatArgs();
			w.log = function() {
				c.log(concatArgs(arguments));
			}
		}

		clear = c.clear; // supported in IE and Fx
	}
	else {
		concatArgs = initConcatArgs();
		w.log = function() { _log(arguments) };
		_log = function(args) { alert(concatArgs(args)) };
	}

})();

Ideas from Simon Mollweide:
Handle error objects, eg. display line number.
Create/use a "console" element for the output.