Browsers create events, and it is the role of Javascript (JS) to handle those events. The main unit of Javascript is the function, and this 12-video course helps identify the role of the function within JS for full stack development. Begin by learning an important application programming interface in JS, the XMLHttpRequest Object—an object allowing developers to transfer data between clients: browser and web server, for example. Next, discover how to use AJAX (Asynchronous JS and XML) to reload content in an HTML page. Take a close look at the Document Object Model (DOM), used to identify and manipulate the content of HTML elements. Learn about developing JSON objects, validating form values, and JS hoisting and scope. Examine the many different ways to use functions in JS; learn how promises work; and apply callbacks within a function. Discover how to simulate inheritance with factory functions, and how to extract variable value by using a closure. The course concludes with an exercise on building a factory function with conventions, ES6 shortcuts, and arrow functions.