Detect existence of event before firing - JavaScript

Detect existence of event before firing - JavaScript

References

Reference NO 1

http://stackoverflow.com/questions/13649610/detect-existence-of-event-before-firing-javascript

Reference NO 2

http://css-tricks.com/snippets/javascript/check-if-function-exists-before-calling/

Reference NO 3

http://www.w3.org/wiki/Handling_events_with_JavaScript

Reference NO 4

http://www.htmlgoodies.com/beyond/javascript/advanced-javascript-event-handling.html

Reference NO 5

http://www.devcurry.com/2011/03/jquery-check-if-function-exists-before.html

Reference NO 6

https://github.com/daleharvey/pouchdb/issues/737

Reference NO 7

http://www.howtocreate.co.uk/tutorials/javascript/domevents

Reference NO 8

http://www.quirksmode.org/js/introevents.html