Testing for console.log statements in IE [duplicate]
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.
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.
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');
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;
}
}
}());
'console' itself needs to be a function, as well as 'log'. So:
if(typeof(console) === 'undefined') {
console = function(){};
console.log = function(){consoleMsg()};
}
Did you try try-catch
:
var debugging = false; // or true
try {
console.log();
} catch(ex) {
/*var*/ console = { log: function() {consoleMsg()} };
}
(function(debug) {
var console;
function wrapConsoleMethod(fnName) {
if(fnName in console)
console[ fnName ] = function(fn) {
return function() {
if(debug)
return fn.apply(console, arguments);
else
alert('Console event in Production Code');
};
}(console[ fnName ]);
else
; // fn not in console
};
if(!('console' in window))
window.console = {
log : function() {}
// ...
};
console = window.console;
wrapConsoleMethod('log');
// ...
})(true /* debug */);
console.log('test');