A front-end web developer’s role is to create the code and mark-up that is rendered by a web browser when you visit a site (read: they control what you see when you visit a webpage).
Let’s take, for example, a listing of events on a webpage. By default, these events are sorted by month, most recent, and then categorized by type. When changing the ‘ALL’ filter to the ‘General’ one, an operation is triggered in the background, and the page gets partially reloaded with our newly queried items. The page doesn’t flicker as it reloads, and we stay put exactly where we are, which makes for a more pleasing web experience.
This can also be used on forms to send data to the server to be stored; again, to keep the page from reloading. AJAX allows a webpage to send and receive data from a web server without triggering a page refresh, allowing for a seamless user experience between the user and the web application.
Cross-Browser Compatibility and Standards Compliance
One example of this is if you have a multi-step form-fill. In this case, the form fill process has certain steps that only occur based on previously entered information. Also, certain data gets populated for certain inputs as well as previous inputs. Doing this without a framework can be very difficult task to achieve. Things can get problematic, and this can happen fast.