How do I disable console.log when I am not debugging?

I would probably abuse the short-circuiting nature of JavaScript's logical AND operator and replace instances of:

console.log("Foo.");

With:

DEBUG && console.log("Foo.");

Assuming DEBUG is a global variable that evaluates to true if debugging is enabled.

This strategy avoids neutering console.log(), so you can still call it in release mode if you really have to (e.g. to trace an issue that doesn't occur in debug mode).

Clobbering global functions is generally a bad idea.

Instead, you could replace all instances of console.log in your code with LOG, and at the beginning of your code:

var LOG = debug ? console.log.bind(console) : function () {};

This will still show correct line numbers and also preserve the expected console.log function for third party stuff if needed.

Since 2014, I simply use GULP (and recommend everyone to, it's an amazing tool), and I have a package installed which is called stripDebug which does that for you.

(I also use uglify and closureCompiler in production)

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Update (June 20, 2019)

There's a Babel Macro that automatically removes all console statements:

https://www.npmjs.com/package/dev-console.macro

Just replace the console.log with an empty function for production.

if (!DEBUG_MODE_ON) {
    console = console || {};
    console.log = function(){};
}