npm install cljs> __NOTE__: work in progress
ClojureScript starter tool
A tool to answer the following questions:
- What would a great first run of ClojureScript look like?
- How do we create that in the clearest and cheapest way possible?
- Should it do everything?
Install
This installs the cljs command:
``
$ npm install -g cljs
_\* cljs is the abbreviation for ClojureScript_
Basics
Using __[Lumo]__, fast experimenting is the default experience.
Try the most basic things as fast as possible.
- REPL
`
$ cljs
cljs.user=> (+ 1 2 3)
6
`
- Run script
`clojure`
;; my_file.cljs
(println (+ 1 2 3))
`sh`
$ cljs my_file.cljs
6
Use dependencies
You can pull in external libraries by specifying them in a plain config file, cljs.edn.cljs
Dependencies are automatically downloaded when running any command or explicitlycljs install
with .
- Dependencies
`edn`
;; cljs.edn
{:dependencies
[[markdown-clj "0.9.94"]]}
`clojure
$ cljs
cljs.user=> (require '[markdown.core :refer [md->html]])
cljs.user=> (md->html "## Hello World")
"
Hello World
"`
- In Script
clojure
;; my_file.cljs
(require '[markdown.core :refer [md->html]]) (println (md->html "## Hello World"))
`
html
$ cljs my_file.cljs
Hello World
`Use Namespaces
If you create a build name that points to a source directory, you can
start organizing files into canonical namespaces.
- Specify src directory
edn
;; cljs.edn
{:dependencies [...]
:builds {:main {:src "src"}}} ;; <-- Source at "src" directory,
;; or use ["src" ...] for multiple.
;; (:main can be any name for the build)
`- Use namespaces
clojure
;; src/example/core.cljs
(ns example.core) (defn hello []
(println "Hello World"))
`
clojure
$ cljs cljs.user=> (require 'example.core)
cljs.user=> (in-ns 'example.core)
example.core=> (hello)
Hello World
`Compile to JavaScript
To run your ClojureScript code without the
command, you can
compile it to a JavaScript output file for use in a browser or elsewhere.
Specify extra config for compiler:- Compiler config
`edn
;; cljs.edn
{:cljs-version "1.9.456" ;; <-- compiler version
:dependencies [...]
:builds {:main {:src "src"
:compiler {:output-to "main.js"}}}} ;; <-- compiler options
`- Build or watch (using the production JVM compiler)
$ cljs build # using this build script
$ cljs watch # using this watch script
- Pretty errors (borrowed from __[Figwheel]__)
clojure
;; modify src/example/core.cljs
(ns example.core) (defn hello) ;; <-- make an incomplete function
`
Compiling src/foo/core.cljs
---- Could not Analyze src/foo/core.cljs line:3 column:1 ---- Parameter declaration missing
1 (ns example.core)
2
3 (defn hello)
^--- Parameter declaration missing
---- Analysis Error : Please see src/foo/core.cljs ----
Develop for the web
Using __[Figwheel]__, you can compile your project with a much more fluid and interactive
developer experience. You get a browser-connected REPL, hot-loading of files
as they change, and an in-page status display.
- Figwheel config
edn
;; cljs.edn
{:cljs-version "1.9.456"
:dependencies [...]
:figwheel {...} ;; <-- optional server-level config
:builds {:main {:src "src"
:figwheel ... ;; <-- optional build-level config
:compiler {...}}}}
`- Run Figwheel
sh
$ cljs figwheel main
`> Try the example provided in this repo:
>
>
sh
> $ cljs figwheel example
>
> cljs.user=>
> `
>
> Open , then modify src-example/example/core.cljs to see
> status messages on your page:
>
> 
Customize build scripts
For direct access to the ClojureScript compiler API,
run with a Clojure file (
.clj not .cljs).
Your Clojure program will be given access to the compiler API and
your config in a cljs-config var.- Custom Build
`clojure
;; build.clj
(require '[cljs.build.api :as b]) ;; <-- official cljs compiler api (let [{:keys [src compiler]} (-> cljs-config :builds :main)]
(b/build src compiler))
`- Run
$ cljs build.clj
[Lumo]:https://github.com/anmonteiro/lumo
[Figwheel Sidecar]:https://github.com/bhauman/lein-figwheel/tree/master/sidecar
[Figwheel]:https://github.com/bhauman/lein-figwheel
[Quick Start]:https://clojurescript.org/guides/quick-start