Now a days, Single Page Applications are very popular due to quick loading and no refresh. Angularjs is very powerful and helpful to build SPA. It extends HTML DOM  having additional attributes and makes more responsive to user actions. AngularJS is completely free, fast and feature reach JavaScript framework.

Also, the code written in Angular JS is cross browser compatible.

Features include Data binding, deep linking, Dependency Injection, MVC, Templates, Directives, Filters, Controller and scope.

You can download JS or use online URL -https://ajax.googleapis.com/ajax/libs/angularjs/1.3.3/angular.min.js

Prerequisites includes basic knowledge of JavaScript, HTML and CSS.