easejs/index.html

<div class="headline">
  <h3>Classical Object-Oriented<br />JavaScript Framework</h3>

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    <div class="inner">
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<p>
  <a href="https://www.gnu.org/" class="subtle" title="GNU's Not Unix!">GNU</a>
  ease.js is a Classical Object-Oriented framework for JavaScript, intended to
  eliminate boilerplate code and &ldquo;ease&rdquo; the transition into
  JavaScript from other Object-Oriented languages. Features include:
</p>

<ul class="features">
  <li><a href="#class-dfn">Simple and intuitive class definitions</a></li>
  <li><a href="#inheritance">Classical inheritance</a></li>
  <li><a href="#traits">Traits as mixins</a></li>
 <li>
   <a href="#access-modifiers">
      Access modifiers (public, protected, and private)
    </a>
  </li>
  <li><a href="#abstract">Abstract classes and methods</a></li>
  <li><a href="#interfaces">Interfaces</a></li>
  <li><a href="#static">Static and constant members</a></li>
  <li><a href="#error">Transparent error subtyping</a></li>
  <li>Support for ECMAScript 3+</li>
</ul>
</div>

<p class="info">
  GNU ease.js is a framework, not a compiler. It may be used wherever JavaScript
  may be used, and supports all major browsers; ease.js also provides support
  for older, pre-ES5 environments by gracefully degrading features (such as
  visibility support) while remaining functionally consistent.
</p>

<p class="info">
  This project is part of the <a href="https://www.gnu.org/">GNU Project</a>.
</p>

<h3 id="class-dfn" class="bigemph">
  Simple and Intuitive Class Definitions
  <span class="anchor"><a href="#class-dfn">&para;</a></span>
</h3>
<p>
  Class definitions closely resemble the familiar syntax of languages like Java
  and PHP.
</p>
<pre class="js">
  <!--%inc scripts/ex/class.js -->
</pre>

<p>
  Classes can be
  <a href="manual/Anonymous-vs_002e-Named-Classes.html" class="man">anonymous or
  named</a>, the latter being more useful for debugging.  Since classes may be
  anonymous, constructors are <a
  href="manual/Constructor-Implementation.html" class="man">styled after
  PHP</a>.
</p>
<pre class="js">
  <!--%inc scripts/ex/class-anon.js -->
</pre>

<p>
  Classes can be instantiated with or without the <tt>new</tt> keyword. Omission
  aids in concise method chaining and the use of
  <a href="manual/Temporary-Instances.html" class="man">temporary instances</a>.
</p>
<pre class="js">
  const inst_a = Foo( "John Doe" );
  const inst_b = new Foo( "John Doe" );

  // temporary instance
  Foo( "John Doe" ).sayHello();
</pre>
<a href="manual/Defining-Classes.html">&rarr; Read more in manual</a>
<a href="#" class="top">&uarr;</a>


<h3 id="inheritance" class="bigemph">
  Classical Inheritance
  <span class="anchor"><a href="#inheritance">&para;</a></span>
</h3>
<p>
  Classes can be extended to create subtypes. Like C++, methods are
  <em>not</em> virtual by default. In Java terminology, all methods are
  final by default. Multiple inheritance, like Java, is unsupported (see
  <a href="#interfaces">Interfaces</a>).
</p>
<pre class="js">
  <!--%inc scripts/ex/class-extend.js-->
</pre>

<p>
  Alternatively, if creating an anonymous subtype, the supertype's
  <tt>extend()</tt> method may be used.
</p>
<pre class="js">
  const SturdyCow = Cow.extend( { /*...*/ } );
</pre>

<p>
  Type checks for polymorphic methods may be performed with
  <tt>Class.isA()</tt>, which is <a
  href="manual/Type-Checks-and-Polymorphism.html" class="man">recommended in
  place of <tt>instanceof</tt></a>.
</p>
<pre class="js">
  <!--%inc scripts/ex/class-poly.js-->
</pre>

<p>
  To prevent a class from being extended, <a href="manual/Final-Classes.html"
  class="man"><tt>FinalClass</tt></a> may be used.
</p>
<pre class="js">
  <!--%inc scripts/ex/class-final.js-->
</pre>
<a href="manual/Inheritance.html">&rarr; Read more in manual</a>
<a href="#" class="top">&uarr;</a>


<h3 id="traits" class="bigemph">
  Traits As Mixins
  <span class="anchor"><a href="#traits">&para;</a></span>
</h3>
<p>
  Trait support was introduced in celebration of becoming a GNU
  project.  It is currently under development and has not yet been
  finalized, but has been included in each GNU ease.js release since v0.2.0,
  and is stable.
</p>
<pre class="js">
  <!--%inc scripts/ex/trait.js-->
</pre>
<p>
  Documentation will be available once some final details are
  finalized.  Until that time,
  the <a href="http://git.savannah.gnu.org/cgit/easejs.git/tree/test/Trait">test
  cases provide extensive examples and rationale</a>.  The following posts
  also summarize some of the features:

  <ul>
    <li><a href="news.html#ac1a036">Preliminary support for traits as mixins</a></li>
    <li><a href="news.html#3005cda">Support for stacked mixins</a></li>
    <li><a href="news.html#3fc0f90">Initial implementation of parameterized traits</a></li>
    <li><a href="news.html#d9b86c1">Class supertype overrides</a></li>
  </ul>
</p>
<a href="#" class="top">&uarr;</a>


<h3 id="access-modifiers" class="bigemph">
  Access Modifiers
  <span class="anchor"><a href="#access-modifiers">&para;</a></span>
</h3>
<p>
  All three common access modifiers&mdash;public, protected and
  private&mdash;are supported, but <a href="manual/Pre_002dES5-Fallback.html"
  class="man">enforced only in ECMAScript 5 and later</a> environments.
</p>
<pre class="js">
  <!--%inc scripts/ex/access-modifiers.js -->
</pre>
<p>
  In the above example, the database connection remains encapsulated within
  <tt>DatabaseRecord</tt>. Subtypes are able to query and escape strings and
  external callers are able to retrieve a name for a given id. Attempting to
  access a private or protected member externally will result in an error.
  Attempting to access a private member from within a subtype will result in an
  error.
</p>
<p>
  Alternatively, a more concise style may be used, which is more natural to
  users of JavaScript's native prototype model:
</p>
<pre class="js">
  <!--%inc scripts/ex/access-modifiers-implicit.js -->
</pre>
<a href="manual/Access-Modifiers.html">&rarr; Read more in manual</a>
<a href="#" class="top">&uarr;</a>


<h3 id="abstract" class="bigemph">
  Abstract Classes and Methods
  <span class="anchor"><a href="#abstract">&para;</a></span>
</h3>
<p>
  If a class contains abstract members, it must be declared as an
  <tt>AbstractClass</tt>. Abstract methods must be overridden by subtypes and
  are implicitly virtual.
</p>
<pre class="js">
  <!--%inc scripts/ex/class-abstract.js-->
</pre>
<a href="manual/Abstract-Members.html">&rarr; Read more in manual</a>
<a href="#" class="top">&uarr;</a>


<h3 id="interfaces" class="bigemph">
  Interfaces
  <span class="anchor"><a href="#interfaces">&para;</a></span>
</h3>
<p>
  ease.js supports the Java concept of Interfaces, which act much like abstract
  classes with no implementation. Each method is implicitly abstract. Properties
  cannot be defined on interfaces.
</p>
<pre class="js">
  <!--%inc scripts/ex/interface.js -->
</pre>

<p>
  Concrete classes may implement one or more interfaces. If a concrete class
  does not provide a concrete implementation for every method defined on the
  interface, it must be declared an <a
  href="#abstract"><tt>AbstractClass</tt></a>.
</p>
<pre class="js">
  <!--%inc scripts/ex/interface-2.js -->
</pre>

<p>
  Polymorphic methods may check whether a given object implements a certain
  interface.
</p>
<pre class="js">
  <!--%inc scripts/ex/interface-3.js -->
</pre>
<a href="manual/Interfaces.html">&rarr; Read more in manual</a>
<a href="#" class="top">&uarr;</a>


<h3 id="static" class="bigemph">
  Static and Constant Members
  <span class="anchor"><a href="#static">&para;</a></span>
</h3>
<p>
  Static members are bound to the class itself, rather than a particular
  instance. Constants are immutable static members (unlike languages like PHP,
  they may use any access modifier). In order to support both
  <a href="manual/Static-Implementation.html" class="man">pre- and
  post-ECMAScript 5 environments</a>, the syntax requires use of a static
  accessor method&mdash;<tt>$()</tt>.
</p>
<pre class="js">
  <!--%inc scripts/ex/static-members.js -->
</pre>
<a href="manual/Static-Members.html">&rarr; Read more in manual</a>
<a href="#" class="top">&uarr;</a>


<h3 id="error" class="bigemph">
  Transparent Error Subtyping
  <span class="anchor"><a href="#error">&para;</a></span>
</h3>
<p>
  Error subtyping (creating your own error types) in ECMAScript is
  notoriously crude, and getting it to work intuitively is even
  harder.  ease.js transparently handles all necessarily boilerplate when
  extending <tt>Error</tt> or its subtypes.
</p>
<pre class="js">
  <!--%inc scripts/ex/error-subtype.js -->
</pre>
<a href="manual/Error-Subtypes.html">&rarr; Read more in manual</a>
<a href="#" class="top">&uarr;</a>


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