Now a days like angular js , have many different writing code for placing UI element. Its directly pre created form of all element. Like auto complete you have to place some short code instead of placing all HTML code for it. So front end development is also big major part. Other thing is load time, performance measurement, DOM element understanding. Image optimization, Bundling CSS and JS. Minified css and jS. all this includes in Development part.
Then Application developer will integrate business logic into the code and we see total working web application and websites.