Enfocus

Enfocus is a DOM manipulation and templating library for ClojureScript. Inspired by Christophe Grand’s Enlive, Enfocus’ primary purpose is providing a base for building rich interfaces in ClojureScript.

You can find examples and documention for enfocus here

If you are unfamiliar with enlive I also recommend taking a look at these links.

David Nolen wrote a nice tutorial
Another tutorial by Brian Marick.

Where do I get support?

On the group

Quick Start

Setup

From any leiningen project file:

[enfocus “0.8.0-SNAPSHOT”]

Then make sure you have your lib folder on your classpath.

For the best development experience, try out cljs-watch. If you do, you’ll need to replace the goog.jar in your CLOJURESCRIPT_HOME/lib with the goog-jar.jar that comes down as a dependency with enfocus.

The Basics

Every great journey starts with “Hello world!”

(ns my.namespace

  (:require [enfocus.core :as ef])

  (:require-macros [enfocus.macros :as em]))

(defn start [] 

  (em/at js/document

    [“body”] (em/content “Hello world!”))
(set! (.onload js/window) start)         

The at form

At the core to understanding Enfocus is the at form used in the
“Hello world!” example above. It comes in two basic flavors listed below:

(at a-node (transform arg1 …))

and
(at a-node

    [selector1] (transform1 arg1 …)

    [selector2] (transform2 arg1 …))

In the first case at is passed a node or node set and a transform and calls the
transform on each element in the node set.

A transform is nothing more than a function that takes a set of arguments and returns a function
that takes a set of nodes. In case of the “Hello World!” example above, we see the use of
(em/content “Hello world!”) this call returns a function that takes node or node set
and replaces the content with “Hello world!”

In the second case, we see at is passed a node or node set and a set of
selector/transform pairs. The selectors are scoped by the node or node set passed in and
the results of each selector is passed on to its partner transformation.

A selector is a string representing a CSS3 compliant selector":http://www.w3schools.com/cssref/css_selectors.asp

Handling Events

Enfocus has event handling. Below is a simple example to add an onclick event handler to a button.

(em/defaction change [msg] 

  [“#button1”] (em/content msg))

(em/defaction setup []

  [“#button1”] (em/listen :click #(change “I have been clicked”)))
(set! (.onload js/window) setup)         

The defaction construct is use here instead defn. defaction
creates a function that calls the at form like discussed above
and passes in js/document as the node to be transformed.

Effects

Enfocus has the concept of effects. Effects are nothing more than transformations
over a period of time. Below is a simple example of a resize effect. Notice how the
effects can be chained.

(em/defaction resize-div [width] 
  ["#rz-demo"] (em/chain 
                 (em/resize width :curheight 500 20)
                 (em/resize 5 :curheight 500 20)))

(em/defaction setup []
  ["#button2"] (em/listen #(resize-div 200)))
	
(set! (.onload js/window) setup)         

Actions, templates and snippets

A snippet is a function that returns a seq of nodes, it can be used as a
building block for more complex templates or actions.

You define a snippet by providing a remote resource, a selector and series of transformations.
The snippet definition below selects a table body from the remote resource
templates/template1.html and grabs the first row. It then fills the content of the row.

  (em/defsnippet snippet2 "templates/template1.html" ["tbody > *:first-child"] 
               [fruit quantity] 
               ["tr > *:first-child"] (em/content fruit)
               ["tr > *:last-child"] (em/content (str quantity)))

A template is very similar to a snippet except it does not require a selector to
grap a sub section, instead the entire remote resource is used as the dom.
If the remote resource is a full html document only what is inside the body tag is
brought into the template.

  (em/deftemplate template2 "/templates/template1.html" [fruit-data] 
                ["#heading1"] (em/content "fruit")  
                ["thead tr > *:last-child"] (em/content "quantity")
                ["tbody"] (em/content
                           (map #(snippit2 % (fruit-data %)) (keys fruit-data))))

An action is a set of transforms that take place on the live dom. below is a
definition of a an action.

(em/defaction action2 [] 
             [".cool[foo=false]"] (em/content (template2 {"banana" 5 "pineapple" 10}))
             ["#heading1"] (em/set-attr :id "new-heading1"))

Transformations

A transformation is a function that returns either a node or collection of node.

Enfocus defines several helper functions:

Supported Enlive Transformations

  content            (content “xyz” a-node “abc”)             

  html-content       (html-content “please no”)

  set-attr           (set-attr :attr1 “val1” :attr2 “val2”)

  remove-attr        (remove-attr :attr1 :attr2) 

  add-class          (add-class “foo” “bar”)

  remove-class       (remove-class “foo” “bar”)

  do→               (do→ transformation1 transformation2) 

  append             (append “xyz” a-node “abc”)

  prepend            (prepend “xyz” a-node “abc”)

  after              (after “xyz” a-node “abc”)

  before             (before “xyz” a-node “abc”)

  substitute         (substitute “xyz” a-node “abc”)

  clone-for          (clone-for [item items] transformation)

                     or (clone-for [item items] 

                          selector1 transformation1

                          selector2 transformation2)

  wrap               (wrap :div) or (wrap :div {:class "foo"}) 

  unwrap             (unwrap)

New Transformations

  set-style          (set-style :font-size “10px” :background “#fff”)

  remove-style       (remove-style :font-size :background)

  listen             (listen :mouseover (fn [event] …))

  remove-listener    (remove-listener :mouseover :mouseout)

  fade-in            (fade-in time step-size)

                     or (fade-in time step-size callback)

  fade-out           (fade-out time step-size)

                     or (fade-out time step-size callback)

  resize             (resize width height ttime step-size)

                     or (resize width height ttime step-size callback)

  move               (move x y ttime step-size)

                     or (move x y ttime step size callback)

  chain              (chain (fade-in ttime step-size) ;serialize async effects

                            (move x y ttime step-size)

                            (fade-out ttime step-size)

                            …)

Currently there is one transformation that is supported by Enlive but not Enfocus. (Patches very welcome!!)

  move               (move [:.footnote] [:#footnotes] content) 

                     ;this will be called relocate in enfocus

Contributing

• Download lieningen
• Download & Install cljs-watch
• Make sure that you have your CLOJURESCRIPT_HOME path setup correctly
• Also ensure that your ClojureScript lib has the goog-jar.jar that comes down as an enfocus dependency

Compile ClojureScript

 git clone git://github.com/ckirkendall/enfocus.git

 cd enfocus/project

 cljs-watch cljs-src '{:output-dir "../sample/resources/public/cljs" :output-to "../sample/resources/public/cljs/enfocus.js"}'

Viewing the Test Page

 cd enfocus/sample

 lein deps

 lein repl

 =>(use 'ring.adapter.jetty)  

 =>(use 'enfocus.ring)

 =>(run-jetty app {:port 3000}) 

Open your browser to:
http://localhost:3000/test.html

Special Thanks!

Christophe Grand for creating enlive and building a simple api for dom manipulation.