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Last active Dec 20, 2015

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How to use browser REPL of ClojureScript with compojure

How to use browser REPL of ClojureScript with compojure

You can do this without compojure. Refer [A minimum setting to use browser REPL of ClojureScript] (

Assumed that you have set leiningen up and can use it.

1. Prepare files

Copy project.clj, repl-test.cljs, minimum_httpd.clj and repl-test.html from this gist or git clone this gist. Move or copy repl-test.cljs under src-cljs directory, minimum_httpd.clj under src and repl-test.html under resources/public

$ git clone
$ cd 6191281/
$ mkdir -p src src-cljs resources/public
$ mv repl-test.cljs src-cljs/
$ mv minimum_httpd.clj src/
$ mv repl-test.html resources/public/

2. Compile

Compile repl-test.cljs into resources/public/repl-test.js.

$ lein cljsbuild once

3. Run a ClojureScript REPL

$ lein trampoline cljsbuild repl-listen
Running ClojureScript REPL, listening on port 9000.
"Type: " :cljs/quit " to quit"

4. Start httpd and open the HTML file

Do below on another terminal

$ lein ring server

This opens http://localhost:3000/ with a new window or tab of your default web browser automatically and it fails with 404 because we didn't define the response for /.

Open resources/public/repl-test.html on a web browser via the httpd


It's enough to add repl-test.html to the address bar of the opened browser.

5. Use the REPL

ClojureScript:cljs.user> (js/alert "Hello world from CLJS REPL!")

If the web browser pops an alert window up, it works.

(ns minimum-httpd
(:use [compojure.core])
(:require [compojure.route :as route]))
(defroutes app
(route/resources "/"))
(defproject repl-test "0.1.0-SNAPSHOT"
:dependencies [[compojure "1.1.5"]]
:plugins [[lein-ring "0.8.6"]
[lein-cljsbuild "0.3.2"]]
:ring {:handler minimum-httpd/app}
:cljsbuild {
:builds [{
:source-paths ["src-cljs"]
:compiler {
:output-to "resources/public/repl-test.js"
:optimizations :whitespace
:pretty-print true}}]})
(ns repl-test
(:require [clojure.browser.repl :as repl]))
(repl/connect "http://localhost:9000/repl")
<script type="text/javascript" src="repl-test.js"></script>
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