Most front-end job postings list a framework next to HTML, CSS and JavaScript. A framework gives you a component model, a way to hold state, a renderer that keeps the page in sync with that state, and usually a router and a build setup. You can build everything in this book without one, but once an interface has dozens of interacting parts, a framework saves you from writing your own, worse one.
Each framework in this section implements the same small component: a text box, an Add #N button whose label counts the items, and a todo list. Versions and licences were checked against the npm registry 2,036 in September 2026; bundle sizes are for that one component, built for production, minified and gzipped.