A ClojureScript library of reusable components for Reagent
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master CircleCI [re-com "0.9.0"]

A ClojureScript library of UI components.

It is built on top of Dan Holmsand's terrific Reagent which, in turn, is a layer over Facebook's trailblazing React.

Just to be clear: this library is 100% ClojureScript. We're not wrapping jQuery plugins here.

Re-com has:

  • 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 app.

Warning: re-com Might Not Be For You (just yet)

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

If you are similar, or if you work on Intranet apps where you can mandate a modern browser, re-com could be ideal for you, right now.

On the other hand, if you target the retail web, you will have to make your own determination, based on availability of support for Flexbox. The entire layout side of this library plus a few of the widgets rely on Flexbox which doesn't work on some older browser versions, specifically IE 9, 10, and 11 (even Edge is not quite perfect yet).

Even when it comes to modern browsers, there will be teething issues. Based on 5 minutes of testing once a month, re-com appears to work reasonably on IE11 and Safari. On the other hand, Firefox (pre version 38) has all the speed of a snail on performance reducing drugs. Version 38 and beyond have a fix for the performance problems caused by nested flexboxes, however as per issue #49 it is still not as fast as Chrome if you are using deeply nested flexbox layouts (much more nested than our demo app).

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. Our main demo app which includes every component, plus all demo code and plenty of yadda yadda, comes to about 167K compressed when using :optimizations :advanced (700K pre-compress). That number includes ReactJS plus the ClojureScript libs and runtime. So, everything.

So, Without Ado Being Any Furthered ...

Still here? Good. I'm glad we got all that negative stuff out the way. I think you're going to like re-com.

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 https://github.com/Day8/re-com.git
    cd re-com
  2. Compiling And Running The Demo

    lein dev-once

This will run the demo, by doing:

  • a clean
  • a compile
  • a load of the right index.html into your default browser
  1. Debugging The Demo

    We love using figwheel to debug.

    To begin a debug session, do this:

    lein dev-auto

This will:

  • clean
  • start the figwheel server & compiler (a terminal window will be started)
  • load the right index.html (specialised for figwheel use)

Your part to play in the process:

  • the initial load of index.html will fail because the figwheel compile hasn't yet finished.
  • be patient - the initial compile might take anything from 10 seconds to 3 mins depending on how many dependencies need to be downloaded (how many are not yet in your local Maven repo).
  • keep an eye on the terminal started by figwheel, waiting for a green Successfully compiled message.
  • you can now refresh the HTML page to see the running demo.


The app is pre-configured with the binaryage/devtools & binaryage/dirac dependencies and initalisations. See initial setup here DEVTOOLS.md

With your app running (see Developing) in your browser Canary/Unstable click on the Dirac extension icon (you can also use standard devtools (F12) if you don't want a Dirac cljs repl)

  1. Run The (erm, modest) Tests

    lein test-once

This will:

  • clean
  • compile the tests
  • load the required test.html into your default browser, so you can see the results.
  1. Debug the tests:

    lein test-auto

Unlike debug which uses figwheel, debug-test uses cljsbuild's auto for recompilation. This probably isn't a good idea, but that's the way it is right now.

  1. 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: https://github.com/Day8/re-com/tree/master/run/resources/public/assets

As far as your index.html is concerned, take inspiration from here: https://github.com/Day8/re-com/tree/master/run/resources/public

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

<link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.5/css/bootstrap.css">

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="http://fonts.googleapis.com/css?family=Roboto:300,400,500,700,400italic" rel="stylesheet" type="text/css">
<link href='http://fonts.googleapis.com/css?family=Roboto+Condensed:400,300' 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 CONTRIBUTING.md for further details on creating issues and pull requests.


Copyright © 2015 Michael Thompson

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