Paul Irish

Paul, using every minification technique I could think of, I came up with this:

 
(function(){
  var log,
    history,
    window = this,
    con = window.console;
 
  window.log = log = function() {
    history.push( arguments );
 
    con && con.log[ con.firebug ? 
      'apply' : 'call']( con, Array.prototype.slice.call( arguments ) );
  };
 
  window.logargs = function( context ) {
    log( context, arguments.callee.caller.arguments );
  };
 
  log.history = history = [];
 
})();
 
// Minified, it's only 242 bytes, a nearly 8% savings in bandwidth!
 
(function(){var b,d,c=this,a=c.console;c.log=b=function(){d.push(arguments);a&&a.log[a.firebug?"apply":"call"](a,Array.prototype.slice.call(arguments))};c.logargs=function(e){b(e,arguments.callee.caller.arguments)};b.history=d=[]})();

How about submitting this to the Firebug/Firebug Lite projects so all can benefit? And submitting bugs in Chrome/WebKit/Firebug to fix the array wrapping issue?

Note that I've built this up quite a bit and posted it on my site:

http://benalman.com/projects/javascript-debug-console-log/

Paul,

When I use your bookmarklet, I get the following error in firebug after it loads:

"Script error. (,0)"

?

Sean

A slight improvement, might be useful for some:

window.log = function()
{
    log.history = log.history || [];
    log.history.push(arguments);
    if (this.console)
    {
        if (arguments.length == 1)
        {
            console.debug(arguments[0]);
        }
        else
        {
            console.log( Array.prototype.slice.call(arguments) );
        }
    }
};

Thanks Paul! I've done something simliar, it doesn't do history, so it's not as useful for actually debugging in IE with firebug lite. It's just a super tiny (52 bytes) snippet that lets you leave console.log statements in your code and not worry about breaking IE or FF. So in case it's useful to anyone:

window.console||(window.console={log:function(){}});

I also made two other, still very small, snippets that do the same thing for the other various console methods (255 and 130 bytes depending on which).

That little project lives here if anyone cares:
https://github.com/andyet/ConsoleDummy.js

Cheers! View Source 4eva!!!

I've run into a scenario where using log() and alert() on a new empty object at the same time yield different results. Alert properly shows that the object is in fact empty while log is showing that it has been modified.

A reference to the object is later passed to another method which modifies it. Whats strange is that log seems to be delayed and is outputting the object in its altered state, even though log is called first. I managed to get around this by cloning the data object and passing the clone to my other method instead.

Have you run into this?

Your wrap does not make

log('%d test,123);

acts the same as

console.log('%d test', 123);

in chrome?
If I want to make it acts the same how could I do?

"Make full use of it and don't you dare type another alert()!"
So true, that made me laugh :)

I wrote a similar lightweight wrapper without a history, and you can force an alert() message if you are debugging in a browser without a console:

var log = function(msg, force) {
    force ? alert(msg) : (console && console.log ? console.log(msg) : null);
};

If anyone is interested, heres the article:
http://www.htmltweaks.com/Debugging_JavaScript_with_the_Console