use of console.log in JavaScript

use of console.log in JavaScript  
https://developers.google.com/chrome-developer-tools/docs/console#basic_operation

use of console

http://blogs.msdn.com/b/cdndevs/archive/2011/05/26/console-log-say-goodbye-to-javascript-alerts-for-debugging.aspx

http://en.wikipedia.org/wiki/Debugging