Jtalk Smalltalk

Jtalk is an implementation of the Smalltalk language that runs on top of the JavaScript runtime. It is designed to make client-side development faster and easier.

Jtalk is written in itself, including the parser and compiler. Jtalk compiles into efficient JavaScript, mapping one-to-one with the equivalent JavaScript. There is no interpretation at runtime.

Try a right now!

Client-side usage

Load the full Jtalk Smalltalk environment with the IDE in your page:

<script src="js/jtalk.js" type="text/javascript"></script>
<link rel="stylesheet" type="text/css" href="css/jtalk.css"/>

Or the deployment JavaScript file only (without the Smalltalk parser or compiler):

<script src="js/jtalk.deploy.js" type="text/javascript"></script>

Read the documentation to learn more about writing applications in Jtalk.

Download

You can get a copy of Jtalk from github or clone the git repository.

Documentation

1. Introduction ¶

This documentation is a work in progress.

Jtalk is a young piece of code and evolves quickly. Some features are still incomplete and you may very well encounter bugs.

Jtalk is an implementation of the Smalltalk-80 language. It allows developers to write client-side heavy web applications in Smalltalk. Jtalk includes an integrated development environment with a class browser, workspace and transcript.

Jtalk includes the following features:

It is semantically and syntaxically equivalent to Pharo Smalltalk (the implementation considered as the reference)
It is written in itself and compiles into efficient JavaScript
A canvas API similar to Seaside to generate HTML
A jQuery binding

2. Differences with other Smalltalk implementations ¶

3. Committing changes to disk with the web-based IDE ¶

The class browser is able to commit changes to disk. The commit category button will send a PUT request with the compiled JavaScript code of all classes in the selected class category in a file named js/CATEGORY.js.

The easiest way to enable committing is probably to setup a webdav with Apache.

The following steps explain how to setup a webdav for Jtalk with Debian, but the setup on OSX and other Linux distros should be similar.

Installing Apache and enabling the dav module

Evaluate the following as root:

~# apt-get install apache2
~# a2enmod dav
~# a2enmod dav_fs

Creating a password for the webdav

htpasswd -c /etc/apache2/htpasswd-webdav USERNAME

Setting up the webdav directory

Add the following lines to the default vhost (in /etc/apache2/sites-available/default):

Alias /jtalk/ "/path/to/jtalk/"
<Directory "/path/to/jtalk/">
    Options Indexes MultiViews FollowSymLinks
    DirectoryIndex index.html
    AllowOverride None
        Order allow,deny
    allow from all

    Dav on

    AuthType Basic
    AuthName "jtalk"
    AuthUserFile /etc/apache2/htpasswd-webdav
    <LimitExcept GET OPTIONS>
            Require valid-user
    </LimitExcept>

</Directory>

Make sure the group www-data has required rights to modify files in the webdav directory.

Restarting Apache

To restart Apache, evaluate the following:

~# /etc/init.d/apache2 restart

and go to http://localhost/jtalk/.

The class browser should now be able to commit changes to disk.

4. The counter example ¶

The following example is the traditional Seaside-like multi-counter application. The buttons at the bottom of each counter increase or decrease the counter.

Open a on the Counter class in the Canvas class category.

Each Jtalk widget is a subclass of Widget. A widget is a graphical component. The #renderOn: method is used to generate HTML using the HTML canvas.