solid

Solid is an open-source JavaScript library for building user interfaces. Its defining design choice is the rejection of the virtual DOM: templates are compiled into real DOM nodes, and updates are applied through fine-grained reactive reactions, so that when a piece of state changes only the code depending on it re-runs. Reactive model Developers declare state with primitives such as createSignal, which returns an accessor and a setter. Derived values are expressed as plain functions that call the accessor, and dependency tracking is automatic — reading reactive state subscribes the surrounding computation to it. Components are ordinary functions that execute once to set up the view, which the README describes as a "render-once" mental model. The documentation illustrates how the compiler extracts static HTML into a template and inserts dynamic expressions so that a single text node can update without re-rendering its parent element. Framework features The library provides JSX, fragments, Context, Portals, Suspense, streaming server-side rendering, progressive hydration, Error Boundaries and concurrent rendering. Built-in state management is offered through Context and Stores, and Resources allow server-loaded data to be treated like other reactive state and rendered responsively with Suspense and concurrent rendering. The README notes SSR and serverless support with streaming and progressive hydration. Compatibility and extensibility Solid is described as isomorphic (client and server rendering) and universal, with custom renderers available for using it in other environments. It is described as web-component friendly and able to author custom elements, with a companion solid-element package. It integrates with JSX and TypeScript, and with the Vite ecosystem; official templates for JavaScript and TypeScript can be scaffolded via degit, and a Babel preset (babel-preset-solid) plus solid-js dependency is the recommended setup, with TypeScript requiring jsx: "preserve" and jsxImportSource: "solid-js". An interactive playground and a tutorial walkthrough are provided on the project site. Stated goals The README claims a small, tree-shakable bundle and performance close to optimized vanilla JavaScript, referencing the JS Framework Benchmark and bundle size comparisons. It emphasizes simplicity, composability and few hidden rules, encouraging declarative code and read-write segregation, while noting that native JavaScript libraries such as D3 can be used directly because the abstractions are minimal. Community and support Support targets the last two years of modern Firefox, Safari, Chrome and Edge on desktop and mobile, with Node LTS and recent Deno and Cloudflare Worker runtimes on the server; IE and similar sunset browsers are explicitly not supported. Testing is backed by SauceLabs. The project maintains Discord and Reddit communities, a contributor base, an Open Collective funding page, and a growing ecosystem of community primitives, component libraries and build-time utilities.