Ko

http://jsfiddle.net/mckennatim/54kex4xq/1/

http://knockoutjs.com/documentation/computedObservables.html

http://stackoverflow.com/questions/6425409/how-to-replace-a-given-index-element-in-knockoutjs

http://www.knockmeout.net/2011/04/utility-functions-in-knockoutjs.html