Testing for console.log statements in IE [duplicate]

Question

Possible Duplicate:
'console' is undefined error for internet explorer

If you have console.log statements in your code, Internet Explorer will throw a JavaScript error (at least in IE7 which is what our intranet users have installed).

I am using Firefox for most of my development testing primarily because of the functionality provided by Firebug (where I use a lot of console statements) but I also need to test in IE.

if I add the following to my JavaScript, the error does not get thrown.

var debugging = false; if (typeof console == "undefined")      var console = { log: function() {} };   

The problem is that I would like to trigger an event if debugging mode is false. If I create a function to test whether debugging is false and do an action (at this point just an alert) but when I try do the following I receive an IE error saying Console is not defined.

var debugging = false; // or true    if (typeof console == "undefined")      var console = { log: function() {consoleMsg()} };     function consoleMsg() {     if(!debugging) {     alert('Console.log event in Production Code'); }    

If someone could help me to fix my code, provide a better way to help me achieve my goal, or direct me to a resource to edumacate myself I would be very appreciative.

Answer 1

You don't have to jump through all these hoops. Simply check if the console exists before using it.

So, instead of:

console.log('foo'); 

Use:

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

...and you won't get any errors.

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Alternatively, you could just check for it at the top of your script, and if it's undefined, just fill it with an empty function:

// At the top of your script: if ( ! window.console ) console = { log: function(){} }; // If you use other console methods, add them to the object literal above  // Then, anywhere in your script: console.log('This message will be logged, but will not cause an error in IE7'); 

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For a more robust solution, use this piece of code (taken from twitter's source code):

// Avoid `console` errors in browsers that lack a console. (function() {     var method;     var noop = function () {};     var methods = [         'assert', 'clear', 'count', 'debug', 'dir', 'dirxml', 'error',         'exception', 'group', 'groupCollapsed', 'groupEnd', 'info', 'log',         'markTimeline', 'profile', 'profileEnd', 'table', 'time', 'timeEnd',         'timeStamp', 'trace', 'warn'     ];     var length = methods.length;     var console = (window.console = window.console || {});      while (length--) {         method = methods[length];          // Only stub undefined methods.         if (!console[method]) {             console[method] = noop;         }     } }());