Awesome Open Source
Awesome Open Source

Idiomatic ClojureScript interface to modern React.js

Discuss at #uix on Clojurians Slack. Bug reports, feature requests and PRs are welcome.

Try it in online REPL

Docs and Guides

API Documentation


Clojars updates are pushed occasionally, depend via Git deps to get the most recent updates.

Clojars Project Clojars Project Clojars Project

{:deps {uix.core {:git/url ""
                  :deps/root "core"
                  :sha "{{replace with commit hash}}"}
        uix.dom {:git/url ""
                 :deps/root "dom"
                 :sha "{{replace with commit hash}}"}
        uix.rn {:git/url ""
                :deps/root "rn"
                :sha "{{replace with commit hash}}"}}}
(require '[uix.core.alpha :as uix])
(require '[uix.dom.alpha :as uix.dom])

(defn button [{:keys [on-click]} text]
  [:button.btn {:on-click on-click}

(defn app []
  (let [state* (uix/state 0)]
      [button {:on-click #(swap! state* dec)} "-"]
      [:span @state*]
      [button {:on-click #(swap! state* inc)} "+"]]))

(uix.dom/render [app] js/root)



Hiccup syntax extension

  • [:div#id.class] or [:#id.class]
  • [:> js/Component attrs & children] - interop with JS components
  • [:<> attrs & children] - React.Fragment
  • [:# {:fallback element} & children] - React.Suspense


React Hooks in idiomatic Clojure style

;; state hook
;; (mutable ref type, re-renders component when mutated)
(let [state (uix/state 0)]
  (swap! state inc)
  @state) ; 1

;; ref hook
;; (mutable ref type, doesn't cause re-renders)
(let [ref (uix/ref 0)]
  (swap! ref inc)
  @ref) ; 1

;; effect hook
  (fn []
    (prn "after update")
    #(prn "before unmount"))

;; convenience macro for uix.core/effect!
(uix/with-effect [deps]
  (prn "after update")
  #(prn "before unmount"))

;; more in uix.core.alpha ns

Attributes syntax extension

Injects provided function into attributes transformation stage. Could be used for various side effects, such as processing styles with CSS-in-JS libraries (see

  (fn [attrs]
    (my-transform-attrs attrs)))

Hiccup pre-compilation (advanced)

NOTE: UIx interpreter is already super fast (3x faster than Reagent and only 2x slower than vanilla React). Use pre-compilation ONLY if you are hitting performance problems.

Compiles Hiccup into inlined React elements at compile-time and hoists constant elements so they can be shared across components in different namespaces (for reference see @babel/plugin-transform-react-inline-elements and @babel/plugin-transform-react-constant-elements). Hoisting is enabled with :optimize-constants compiler option, which is automatically enabled for :optimizations :advanced.

  [:h1 "Title"])

;; emits this
  $$typeof: Symbol.for("react.element"),
  key: null,
  ref: null,
  props: { children: "Title" },
  _owner: null

Lazy loading components

Loading React components on-demand as Closure modules. See code splitting guide and how lazy loading is used in React with Suspense: guide.

  '[uix.components :refer [ui-list]])

[:# {:fallback "Loading..."}
  (when show?

Server-side rendering

UIx can be used for SSR or usual templating in both JVM and JavaScript runtimes

Server-side rendering in JVM

See an example in

(uix.dom/render-to-string element) ;; see
(uix.dom/render-to-static-markup element) ;; see

;; Streaming HTML
(uix.dom/render-to-stream element {:on-chunk f}) ;; see
(uix.dom/render-to-static-stream element {:on-chunk f}) ;; see

Server-side rendering in JS

SSR works in JavaScript environment via React's serializer using same API.

  1. Add ReactDOMServer into your dependencies (as cljsjs/react-dom-server or any other way)
  2. Run (uix.dom/render-to-string element)


  • Hiccup interpretation clojure -A:dev:benchmark:bench-front
  • SSR on JVM clojure -A:dev:benchmark:bench-ssr

Hiccup interpretation

react x 23866 ops/s, elapsed 419ms
uix-interpret x 11848 ops/s, elapsed 844ms
reagent-interpret x 4031 ops/s, elapsed 2481ms


lib test 1 test 2 test 3
rum 107.8 µs 3.6 ms 7.7 ms
uix 120.8 µs 3.8 ms 8.1 ms
uix streaming 115.7 µs 3.4 ms 7.6 ms
hiccup 205.7 µs 6.5 ms 16.6 ms

TodoMVC bundle size

lib size gzip
rum 254KB 70KB
reagent 269KB 74KB
uix 234KB 65KB


When developing with Figwheel it is recommended to mark root render function with ^:after-load meta, so Figwheel can update UI tree once the code was re-evaluated.

(ns ^:figwheel-hooks my.ns)

(defn ^:after-load render []
  (uix.dom/render [app] js/root))

React DevTools

When inspecting UI tree in React DevTools, filter out memo components to get cleaner view of components tree.



Note: to ensure you're using the right Node.js version, you can use nvm and run nvm use once in the directory. Otherwise the Node.js version you use is in the .nvmrc file. See nvm repo for more documentation.

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