authentication of html pages

I was working with WebForms in visual studio, but now I'm going to work with HTML, css, javascript, I'm going to consume a webservice with ajax, so all programming will be client side, there will be no programming on the server. My question is how to authenticate the pages after login, I read about SessionStorage (html5), localStorage (html5), cookies, angular js and more that I can not remember now. What is the best option or an option that gives me security? If you have any examples, thank you very much.