If you are going to have this on a public site or something, anyone with little knowledge on using the developer tools can read your debug messages. Depending on what you are logging, this may not be a desirable behavior.

One of the best approaches is to wrap the console.log in one of your methods, and where you can check for conditions and execute it. In a production build, you can avoid having these functions. This Stack Overflow question talks in details about how to do the same using the Closure compiler.

So, to answer your questions:

1. Yes, it will reduce the speed, though only negligibly.


2. But, don't use it as it's too easy for a person to read your logs.


3. The answers to this question may give you hints on how to remove them from production.