I'm curious if it is possible to include a template system like HandlebarsJS handlebarsjs.com?
Wherein I would like to achieved is include html file to my pages. Example is include the navigation (nav.html) to each file (index.html, contact.html etc.) Also I would like to manipulate some conditions inside the html file. It is possible, advisable, runnable or executable when the app was built?
Absolutely, you can install it on the client side just as you would for a webpage. The best option is probably to "precompile it". Check out http://handlebarsjs.com/precompilation.html for more details.