The problem: you have a static site and you want to add a sprinkle of interactivity, using Clojure, without bloating your build.

With cljs-ultralight we try to achieve this dream:

• sub-1k build sizes.
• Concise functions for common UI operations.
• Clojure language & tooling (live-reload, editor integration, repl etc.)

cljs-ultralight is a group of functions to help you keep your cljs builds tiny when building simple UIs. You can easily keep your bundle size under 1k uncompressed with this.

Here is a blog post about making ClojureScript UIs in 500 bytes.

{:deps {io.github.chr15m/cljs-ultralight {:git/tag "LATEST-GIT-TAG" :git/sha "LATEST-GIT-SHA"}}}

Alternatively you can use npm to install it into node_modules.

npm i cljs-ultralight

You'll have to manually add the sources in your shadow-cljs.edn if you use npm to install it.

:source-paths [... "node_modules/cljs-ultralight/src"]

(ns myapp.core
  (:require [ultralight.core :as u]))

(-> (u/$$ "#my-button")
    (u/evt "click"
           #(js/alert "Clicked!")))

The source code is so small as to be self-documenting. 😅 When this changes I will add more documentation.

Check out the demo for more examples.

• npm run build to build it.
• npm run size to see the build size (will automatically build first).
• npm run watch to develop on it.

To get tiny build sizes cljs-ultralight tries to use native JS constructs where ever possible. You should do the same if you want those small build sizes. Including a single equality operator for example will balloon a basic build size from 1k to 94k. Here are some rules to follow to avoid this:

• Use #js {}, #js [], etc. instead of Clojure data types.
• Use coercive-= instead of =.
• Use (.concat string-1 string-2) instead of (str string-1 string-2).
• Use (.map #js [1 2 3] (fn [i] ...)) etc. instead of (map (fn [i] ...) [1 2 3]).
• Use #(... %) instead of partial.
• Use js/console.log instead of print.

The library applied-science/js-interop works well too.