Comments on: Little JavaScript hints, episode 1: prevent console.log breakage

By: Michael J. Ryan

Michael J. Ryan — Wed, 22 Jul 2009 17:44:10 +0000

here’s mine…

//define a single reference for an empty function
if (typeof Function.empty == ‘undefined’)
Function.empty = function(){};

//stub out full console object — will allow debug/log statements to be left in place
if (typeof console == ‘undefined’)
console = {
“assert”: Function.empty,
“count”: Function.empty,
“debug”: Function.empty,
“dir”: Function.empty,
“dirxml”: Function.empty,
“error”: Function.empty,
“group”: Function.empty,
“groupEnd”: Function.empty,
“info”: Function.empty,
“log”: Function.empty,
“profile”: Function.empty,
“profileEnd”: Function.empty,
“time”: Function.empty,
“timeEnd”: Function.empty,
“trace”: Function.empty,
“warn”: Function.empty
};

By: Sean McArthur

Sean McArthur — Fri, 19 Dec 2008 17:38:00 +0000

Even though the likelihood of this causing problems is small, I still wouldn’t compare it to the variable undefined. That comparison is only valid because you have never created that variable. Say for some weird reason you were to say:

var undefined = null;

Your if statement will be false. Use:

typeof window['console'] === ‘undefined’;

By: kangax

kangax — Fri, 19 Dec 2008 17:38:00 +0000

Good to see you writing again!

I don’t think one needs such precision (`=== undefined`) : ) Why skip things like `null` or string values (that would still throw errors when trying to invoke)

I usually use:

if (typeof console.log != ‘function’) {
console.log = function(){ /* … */ }
}

By: Thomas

Thomas — Fri, 19 Dec 2008 17:38:00 +0000

@kangax Cools! I think I just like the === operator too much!

Btw, won’t "typeof console.log" barf when there is no console object? Do you wrap it in anything else?

By: kangax

kangax — Fri, 19 Dec 2008 17:38:00 +0000

Yep, it most certainly will barf. I was only making a point about the actual existence check : )

Here’s a `console.js` that I include in my projects (before any other scripts) http://gist.github.com/38358

By: Collin Allen

Collin Allen — Fri, 19 Dec 2008 17:38:00 +0000

Do these Firebug tricks work with Firebug 1.3bX? Even something simple like window.console.log=function(){}; doesn’t seem to stop console.log("test"); from working.

To the best of my knowledge, the Firebug team changed how the console object works in 1.3 (more specifically, how it interacts with the non-privileged web page), which might be the cause.

By: Rakesh Pai

Rakesh Pai — Fri, 19 Dec 2008 17:38:00 +0000

Assuming you are using Prototype, and if you want to stub out _all_ console methods, here’s how.

if(!window.console) { window.console = {}; }

$A([ "assert", "count", "debug", "dir", "dirxml", "error", "group", "groupEnd", "info", "log", "profile", "profileEnd", "time", "timeEnd", "trace", "warn" ]).each(function(method) { if(!console[method]) { console[method] = function(){}; } });

By: fidel Karsto

fidel Karsto — Fri, 19 Dec 2008 17:38:00 +0000

@gonchuki: The point in referencing the Prototype.emptyFunction is in not creating a new function object each time you need a placeholder function, but instead reference to an already existing one. Remember that every object (functions in JS are object too) need a space in memory, whereas a reference is only a pointer to an adress.

This might sound narrow-minded, but imagine large projects where every objects counts – especially with our old friend IE6, which gets pretty fast blasted with objects.
But I’m sure Thomas will handle this in his new book.

By: gonchuki

gonchuki — Fri, 19 Dec 2008 17:38:00 +0000

what stops me from using function(){} ?

I don’t get why the need to plug Prototype when using a *literal* empty function is a lot more clear.

btw, for people that give firebug a serious use, defining log is not enough, this is the desirable solution:

window.console = {log: function(){}, warn: function(){}, error: function(){}, info: function(){}};

By: Thomas

Thomas — Fri, 19 Dec 2008 17:38:00 +0000

@gonchuki You’re right of course that you can just use plain ol’ function(){}, but sometimes I prefer having more literal code (when I will glance over this code later, using emptyFunction instantly makes clear what’s going on).

I doubt that the warn/error/info functions are that much used (very rarely do so myself), but YMMV. Thanks for the snippet!