Question

I have seen jquery-ui-1.8.11.js verify console.log functionality by doing

if (this.debug)
   console.log()

I have also seen people define an anonymous function that is a no-op for browsers with no console logging like IE7.

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

---

Is there a technical difference or are both functionally equivalent?

Answer 1

Both of those do something else. The first code suppresses logging messages unless a flag is set. The people who develop jQuery UI need logging when working on it, and turn it on. But people using the library don’t want to have their console cluttered by log messages from libraries, so it’s off by default. It lets you turn off logging even when the browser supports it – that regular users on IE7 don’t get script errors is a (possibly intended) side effect.

The second code defines a dummy console.log(), so you can call the method without checking if it exists everywhere. It will not suppress logging on browsers where it’s supported.