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Frontend Development › UI Frameworks & Components

UI Framework

Libraries like React, Vue, Svelte and Angular for building interfaces.

Frontend Engineer · Junior · core

Also known as: frontend framework, JavaScript framework, React, Vue, Svelte, Angular

A UI framework (or library) like React, Vue, Svelte, Angular or Solid helps you build interfaces from components and keeps the screen in sync with your data, so you don’t update the DOM by hand.

Compare plain JavaScript:

let count = 0;
const label = document.querySelector("#label");
button.addEventListener("click", () => {
  count++;
  label.textContent = `Clicked ${count} times`;    // you must remember to update the page
});

with a framework, where you describe what the UI looks like for a given state, and it handles the updates:

const [count, setCount] = useState(0);
return <button onClick={() => setCount(count + 1)}>Clicked {count} times</button>;

This is declarative UI: UI = function of state.

What they provide

  • A component model for reuse.
  • Reactivity: updating exactly what changed, using techniques such as a virtual DOM or fine-grained signals.
  • Often tools for routing, forms, data and testing, directly or through a meta-framework (Next.js, Nuxt, SvelteKit…).

Library or framework?

React is technically a library for building UI (you add routing and data tools yourself), whereas Angular is a full framework with those included. In practice people use “framework” for all of them.

Choosing one

They solve the same problem differently, and none is universally best. Teams usually decide by:

  • what the team already knows, and how easy it is to hire for,
  • the ecosystem (libraries, tooling, community),
  • project size and needs (SEO, server rendering, mobile),
  • the maturity and long-term support of the project.

See choosing a framework. If you’re learning: get JavaScript, HTML, CSS and the browser basics solid first. Frameworks change faster than the language underneath them, and the concepts (components, state, props, data flow) transfer between them.