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A ClojureScript library of UI components for Reagent.

Re-com provides:

  • familiar UI widgetry components such as dropdowns, date pickers, popovers, tabs, etc.
  • layout components, which arrange widgets vertically and horizontally, within splitters, etc. Plus components which put borders around their children. These various pieces can be arbitrarily nested to create sophisticated layouts.
  • a mostly Bootstrap look, mixed with some Material Design Icons.

In short, re-com attempts to provide the kind of UI basics you'd need to build a desktop-class SPA app.

Warning #1: Uses Flexbox

The entire layout side of this library plus a few of the widgets rely on Flexbox

Pretty much every modern browser that you probably care about has support for Flexbox so this is probably a non-issue these days, unless you need to support old versions of IE.

We build desktop-class apps to run in controlled browser environments like Electron. So, we know we're dealing with Chrome.

Warning: No Mobile Focus

We can also confirm that none of the components have been designed with mobile in mind, and that there's no attempt to handle media queries. We said we had a desktop app focus, right?

Neither have we been worried too much about code size because other design goals have taken precedence. To give you some idea, our main demo app which includes every component, plus all demo code and plenty of yadda yadda explanatory strings, comes to about 167K compressed when using :optimizations :advanced (700K uncompressed). That number includes ReactJS plus the ClojureScript libs and runtime. So, everything.

So, Without Ado Being Any Furthered ...

Start by looking at the demo.

Navigating The Source

When you are running the demo app, you'll see hyperlinks, to the right of page titles, which take you to the associated source code. That's a convenient way to navigate to either the components themselves or the demo code.

When browsing more generally, look in the src directory or this repo, you'll notice two sub-directories:

  • re-com - the library itself - the components
  • re-demo - the demo app, which shows how to use the components

Useful Commands

  1. Getting The Repo

    git clone
    cd re-com
  2. Compiling And Running The Demo

    lein watch

This will run the demo, by doing:

  • a clean
  • a compile

Wait until [:demo] Build completed. is displayed in the console indicating the dev HTTP server is ready.

Now you can open http://localhost:3449/ in your browser.

  1. Run The (erm, modest) Tests

    lein ci

This will:

  • clean
  • compile the tests
  • compile in release mode as a basic optimized build check
  1. Run or Debug the tests:

    lein watch
  2. Deploy The Demo App To S3 bucket

    This will only work if you have the right credentials in your env:

    lein deploy-aws

Using re-com

re-com is available from clojars. Add it to your project.clj dependencies:

Clojars Project

You should now be able to require the re-com.core namespace, which exposes all of the API functions documented in the re-demo example app.

You'll then need to include these asset folders in your app:

As far as your index.html is concerned, take inspiration from here:

In particular, you'll need bootstrap (assumedly via a CDN):

<link rel="stylesheet" href="//">

And a reference to these two CSS files (make sure re-com.css appears after bootstrap.css):

<link rel="stylesheet" href="assets/css/material-design-iconic-font.min.css">
<link rel="stylesheet" href="assets/css/re-com.css">

And a reference to the Roboto fonts (but this can be overridden relatively easily):

<link href=",400,500,700,400italic" rel="stylesheet" type="text/css">
<link href=',300' rel='stylesheet' type='text/css'>

Reagent comes bundled with a matching version of ReactJS, so you don't need to include it explicitly.


If you decide to use re-com, consider also using re-frame (an MVC-ish framework).

Although both re-frame and re-com can be used independently of each other, they dovetail well.

Lein Template

See re-frame-template.

The Missing Components

  • tree (not hard, just haven't needed one yet)
  • menus - there's a dropdown, but no cascading menus
  • accordion
  • maybe a dockable LHS navbar
  • virtual grid. Straight v-box is good enough at small grids, so no problem there. But when the number of rows gets huge, you need a widget which does virtual rows, otherwise there's just too much DOM and there's performance problems. Can we use Fixed Data Tables for React?
  • drag and drop.
  • animations / transitions. We have ideas. They seem clunky.
  • Focus management - When the user presses tab, to which field does focus move?


  1. Where the docs are wrong or fall short, write up something better. Because our docs take the form of an app written in ClojureScript using re-com, you're actually exercising your knowledge of re-com as you do this.
  2. See the list of missing components above. You'll have to produce the component itself, including a params spec, plus the extra page in the demo app.
  3. Test re-com on new browsers and iron out any quirks. Our focus is strictly Chrome.

When creating new components, we have found it useful to use the CSS from existing JavaScript projects (assuming their licence is compatible with MIT) and then replace the JavaScript with ClojureScript. Reagent really is very nice.

Also, please refer to for further details on creating issues and pull requests.


Copyright © 2015-2019 Michael Thompson

Distributed under The MIT License (MIT) - See LICENSE.txt

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