Frameworks give you components (reusable UI pieces), reactivity (UI updates when data changes without manual DOM updates), and a structured way to manage state and side effects. You write less boilerplate than with vanilla JS and get a clearer mental model for large apps.

Pick by team experience, ecosystem (libraries, jobs), and project size. All major frameworks can build the same products; the difference is in style and ecosystem.

React: JSX, virtual DOM, huge ecosystem and job market. Unidirectional data flow; you manage state with useState/useContext or external stores. Vue: single-file components with templates, gentler learning curve, strong official tooling.

Svelte: compiles to small, fast JS; no virtual DOM at runtime. Less boilerplate, smaller bundles. All three support components, state, and routing; concepts (components, props, state, effects) transfer between them.

React has the most tutorials and job postings; a good default. Vue if you prefer templates and a more opinionated structure. Svelte if bundle size and simplicity matter. Learning one well makes the others easier.

[MDN – JS frameworks](https://developer.mozilla.org/en-US/docs/Learn_web_development/Getting_started).