HTML5, CSS, Javascript: Best Practices in developing Web and Mobile applications 2015

The rapid growth in mobile device usage is continuing to dramatically change the way people live, work, and interact over the Web. The demand on developers to build elegant, intuitive, and easy to use mobile apps has never been greater. This has fueled significant changes in Web and mobile app development strategies. Can you afford to be left behind? Over the last three years, HTML5, Responsive Web Design, and Single-Page Apps have moved into the mainstream for enterprise mobile app development. The growing adoption of open Web-based standards and updated APIs for delivering mobile experiences are closing some of the performance gaps previously seen in native apps. Additionally, JavaScript is constantly evolving and developers are finding new techniques and Best Practices. In order to more efficiently and cost effectively build apps that support all of the different mobile platforms, operating systems, device types and screen sizes, enterprises are increasingly turning to hybrid and Web app development strategies. Many mobile app developers are now wondering:

What is the best app development strategy for my project – web, hybrid, or native?
Should I use JavaScript or one of the alternatives (e.g. CoffeeScript, Dart)?
When does it make sense to use a framework such as Backbone or Angular?
How can I support modern techniques with older browsers?
What are the implications to the applications that I have already built and will build in the future?