js override console.log if not defined

Question

Which solution do you recommend, the second is simpler ( less code ), but there are drawbacks on using it ?

First: (Set a global debug flag)

// the first line of code var debug = true; try { console.log } catch(e) { if(e) { debug=false; } }; // Then later in the code if(debug) { console.log(something); }

Second: override console.log

try { console.log } catch(e) { if (e) { console.log = function() {} } }; // And all you need to do in the code is console.log(something);

Andy E · Accepted Answer · 2010-09-22 09:55:14Z

56

Neither, but a variation of the second. Lose the try...catch and check for existence of the console object properly:

if (typeof console == "undefined") { window.console = { log: function () {} }; } console.log("whatever");

edited Sep 22, 2010 at 9:55

answered Sep 22, 2010 at 9:35

Andy E

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5 Comments

Tim Down Over a year ago

Presumably you either want to do this.console = ... or var console = ...? As you have it at the moment, you'd get an error in ECMAScript 5 strict mode.

Andy E Over a year ago

@Tim: thanks, it was an oversight. I think window.console would be best for portability.

Tim Down Over a year ago

Portability in the sense of being able to move this code into a function, rather than portability between environments?

jcolebrand Over a year ago

Should you test typeof window.console since you're setting window.console later? Or should window. be removed?

Tim Holt Over a year ago

Definitely check out the solution by Suresh below - he is also defining other console methods that may not be defined. See developer.mozilla.org/en-US/docs/Web/API/Console for a full list of all console methods available and what the browser support is like.

Jameson Quinn · Accepted Answer · 2011-05-13 16:42:38Z

Or, in coffeescript:

window.console ?= log:-> #patch so console.log() never causes error even in IE.

Community · Accepted Answer · 2017-05-23 11:50:35Z

3

EDIT: Andy's answer is way more elegant than the quick hack I've posted below.

I generally use this approach...

// prevent console errors on browsers without firebug if (!window.console) { window.console = {}; window.console.log = function(){}; }

edited May 23, 2017 at 11:50

CommunityBot

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answered Sep 22, 2010 at 9:40

Frankie

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2 Comments

Simon E. Over a year ago

I like your version Frankie, but I'm not sure that it works safely across all browsers. I remember using this and still getting occasional issues with one of the IE versions, perhaps because console object is only defined when the console window is open in IE9. I think I had to do an 'undefined' check like Andy E suggested.

Frankie Over a year ago

@Simon this comes late as a comment but only saw it today. Andy's solution is way more elegant than this quick hack I've posted. You should use that instead.

Community · Accepted Answer · 2016-02-16 15:53:56Z

1

I've faced a similar bug in my past, and I overcame it with the code below:

if(!window.console) { var console = { log : function(){}, warn : function(){}, error : function(){}, time : function(){}, timeEnd : function(){} } }

edited Feb 16, 2016 at 15:53

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answered Jun 17, 2014 at 10:29

Suresh

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3 Comments

Radu M. Over a year ago

How is this different than Frankie or Andy_E answers ?

Tim Holt Over a year ago

The answer by Suresh is better in that he is also defining other methods that will not be defined along with log. Check out developer.mozilla.org/en-US/docs/Web/API/Console for a full list of all functions that may (or may not) be defined.

Glenn Lawrence Over a year ago

This won't work if it's called from within a function. Instead of var console it should be window.console or just console

David · Accepted Answer · 2012-06-19 21:27:28Z

I came across this post, which is similar to the other answers:

http://jennyandlih.com/resolved-logging-firebug-console-breaks-ie

Mike Kormendy · Accepted Answer · 2012-11-23 21:47:53Z

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The following will achieve what you are looking for:

window.console && console.log('foo');

answered Nov 23, 2012 at 21:47

Mike Kormendy

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Comments

Sean · Accepted Answer · 2013-07-18 17:31:08Z

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

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