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A React-inspired frontend library for Scala.js. Build user interfaces with function components, hooks, and a typed DSL: an immutable VNode tree describes the UI, and a reconciler diffs each new tree against the live DOM and patches only what changed.

riposte — in fencing, the swift counter-thrust that follows a parry. Here: an event or state change comes in, the reconciler diffs (parry), and patches the DOM in answer (riposte). The word traces back through Italian sword-fighting to Latin respondēre — "to respond."

import io.github.edadma.riposte.*
import org.scalajs.dom
val Counter = view {
 val (count, _, update) = useState(0)
 button(onClick := (_ => update(_ + 1)), s"Count: $count")
}
@main def run(): Unit =
 render(Counter(), dom.document.getElementById("app"))

Full documentation lives at riposte.edadma.dev.

• Getting started — install and mount your first component
• Guide — components & the DSL, hooks, shared state, routing, data fetching, forms
• Component library (salle) — styled, skinnable widgets, one page per component
• Reference — the published modules and their APIs

Riposte ships as six independently published artifacts under io.github.edadma; the siblings depend on the core transitively. The core itself is a thin DOM host over vdom — a host-agnostic engine (the VNode model, reconciler, hooks runtime, and scheduler) that names no platform type and is pulled in transitively. You depend on riposte, not vdom.

libraryDependencies += "io.github.edadma" %%% "riposte" % "0.3.0"
libraryDependencies += "io.github.edadma" %%% "riposte-atoms" % "0.3.0"
libraryDependencies += "io.github.edadma" %%% "riposte-router" % "0.3.0"
libraryDependencies += "io.github.edadma" %%% "riposte-query" % "0.3.0"
libraryDependencies += "io.github.edadma" %%% "riposte-forms" % "0.3.0"
libraryDependencies += "io.github.edadma" %%% "riposte-salle" % "0.3.0"

• vdom/ — the host-agnostic core (VNode, reconciler, hooks, scheduler, HostConfig), a crossProject(JS, JVM); riposte hosts the JS build, the JVM build runs headless reconciler/hooks tests
• core/ — the riposte library: the DOM host for vdom (its HostConfig, the HTML/SVG DSL, the DOM hooks) plus the re-export of vdom's API under io.github.edadma.riposte
• atoms/ — riposte-atoms, atomic state built on the core's useSyncExternalStore seam
• router/ — riposte-router, client-side routing on the same public seam
• query/ — riposte-query, an async server-state cache built on riposte-atoms
• forms/ — riposte-forms, a react-hook-form-style form layer on the core's public API
• salle/ — riposte-salle, a styled component library built on the core's DSL + hooks
• demo/ — a runnable showcase (its own subproject, never published)
• salle-demo/ — a runnable showcase for salle (its own subproject, never published)
• salle-e2e/ — a Playwright harness driving salle components in a real browser (never published)
• the repo root is a thin aggregator; a task run there fans out to every module

sbt test # every module (vdom JVM+JS, core + atoms + router + query + forms + salle)
sbt vdomJVM/test # the host-agnostic core, headless on the JVM (TestHost)
sbt vdomJS/test # the same suite on JS
sbt riposte/test # just the library (project id is `riposte`, in core/)
sbt atoms/test # just the atoms module
sbt router/test # just the router module
sbt query/test # just the query module
sbt forms/test # just the forms module
sbt salle/test # just the salle component library
sbt demo/fastLinkJS # build the demo's JS
sbt salleDemo/fastLinkJS # build the salle demo's JS

Tests run under a real DOM via jsdom (npm install fetches it). To see the demo, build its JS, then serve demo/ (e.g. cd demo && python3 -m http.server) and open index.html.

The salle component library also has a Playwright suite that drives the components in a real Chromium (salle-e2e/), covering interactions jsdom can't — focus, pointer, layout:

npm run e2e # build the harness bundle, then run the Playwright specs
npm run e2e:build # just build the harness JS (sbt salleE2E/fastLinkJS)
npm run e2e:run # run the specs against an already-built bundle
npm run e2e:ui # the same, in Playwright's interactive UI

ISC