How to determine the Opera browser using JavaScript

Question

I want to determine that the browser of the client machines in Opera or not using JavaScript, how to do that?

Answer 1

Now that Opera uses the Chrome rendering engine, the accepted solution no longer works.

The User Agent string shows up like this:

Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/28.0.1500.52 Safari/537.36 OPR/15.0.1147.132

The only identifier for Opera is the OPR part.

Here's the code I use, which should match the old Opera or the new Opera. It makes the Opera var a boolean value (true or false):

var Opera = (navigator.userAgent.match(/Opera|OPR\//) ? true : false);