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);

Solution 1

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");

Solution 2

Or, in coffeescript:

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

Solution 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(){};
}

Solution 4

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(){}
    }
}

View more solutions

Comments

[Tim Down]

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]

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

[Tim Down]

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

[Simon East]

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.

[jcolebrand]

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

[Frankie]

@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.

[Radu Maris]

How is this different than Frankie or Andy_E answers ?

[Tim Holt]

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.

[Tim Holt]

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.

[Glenn Lawrence]

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