Acerca de JavaScript

  • Enlace amigable (slug) de la revisión: JavaScript/Acerca_de_JavaScript
  • Título de la revisión: Acerca de JavaScript
  • Id de la revisión: 66472
  • Creada:
  • Creador: inma_610
  • ¿Es la revisión actual? No
  • Comentario page created, 629 words added

Contenido de la revisión

¿Qué es JavaScript?

JavaScript® es el lenguaje de scripts para objetos desarrollado por Netscape que se utiliza en millones de páginas web y aplicaciones de servidor en todo el mundo. JavaScript de Netscape es un superconjunto del lenguaje de scripts estándar de la edición de ECMA-262 3 (ECMAScript) que presenta sólo leves diferencias respecto a la norma publicada. Contrariamente a la falsa idea popular, JavaScript no es "Java interpretativo".

Contrariamente a la falsa idea popular, JavaScript no es "Java interpretativo". En pocas palabras, JavaScript es un lenguaje de programación dinámico que es compatible con prototipos basados en la construcción de objetos. La sintaxis básica es similar a Java y C + + con la intención de reducir el número de nuevos conceptos necesarios para aprender el lenguaje. Language constructs, such as if statements, for and while loops, and switch and try ... catch blocks function the same as in these languages (or nearly so.)

JavaScript can function as both a procedural and an object oriented language. Objects are created programmatically in JavaScript, by attaching methods and properties to otherwise empty objects at run time, as opposed to the syntactic class definitions common in compiled languages like C++ and Java. Once an object has been constructed it can be used as a blueprint (or prototype) for creating similar objects.

JavaScript's dynamic capabilities include runtime object construction, variable parameter lists, function variables, dynamic script creation (via eval), object introspection (via for ... in), and source code recovery (JavaScript programs can decompile function bodies back into their source text)

Intrinsic objects are Number, String, Boolean, Date, RegExp, and Math.

For a more in depth discussion of JavaScript programming follow the JavaScript resources links below.

What JavaScript implementations are available?

mozilla.org hosts two JavaScript implementations. The first ever JavaScript was created by Brendan Eich at Netscape, and has since been updated (in JavaScript 1.5) to conform to ECMA-262 Edition 3. This engine, code named SpiderMonkey, is implemented in C. The Rhino engine, created primarily by Norris Boyd (also at Netscape) is a JavaScript implementation in Java. Like SpiderMonkey, Rhino is ECMA-262 Edition 3 compliant.

Each mozilla.org JavaScript engine exposes a public API applications can call on for JavaScript support. By far, the most common host environment for JavaScript is web browsers. Web browsers typically use the public API to create 'host objects' responsible for reflecting the DOM into JavaScript.

Another common application for JavaScript is as a (web) server side scripting language. A JavaScript web server would expose host objects representing a HTTP request and response objects, which could then be manipulated by a JavaScript program to dynamically generate web pages.

For more information on embedding JavaScript in your own applications, follow either the SpiderMonkey or Rhino links below, or visit us on the netscape.public.mozilla.jseng newsgroup.

JavaScript resources

SpiderMonkey
Information specific to JavaScript in C engine (aka SpiderMonkey) embedding.
Rhino
Information specific to the JavaScript implementation written in Java (aka Rhino).
Language resources
Pointers to published JavaScript standards, LiveConnect documents, and work on JavaScript 2.0.
Tamarin Project
Information on the the high-performance, open-source virtual machine for JavaScript 2.0.
A re-introduction to JavaScript
Core JavaScript 1.5 Guide and Core JavaScript 1.5 Reference
Scripting resources
Pointers to JavaScript scripting resources, including recommended reading, online references and tutorials, and sample code.
Projects page
Lists other projects using the open source JavaScript engines.
Test library page
Information about the core JavaScript test suite.
mozilla.dev.tech.js-engine
The newsgroup for discussion about the JavaScript engines.
comp.lang.javascript
The newsgroup for general discussion about ECMAScript, mostly (though not necessarily) as it pertains to browsers.

JavaScript is a trademark or registered trademark of Sun Microsystems, Inc. in the U.S. and other countries.

{{ languages( { "en":"en/JavaScript/About_JavaScript"} ) }}

Fuente de la revisión

<h2>¿Qué es JavaScript?</h2>
<p><a class="external" href="http://www.instantweb.com/~foldoc/foldoc.cgi?query=javascript">JavaScript</a><sup>®</sup> <span class="goog-gtc-unit" id="goog-gtc-unit-2"><span class="goog-gtc-translatable goog-gtc-from-human" dir="ltr">es el lenguaje de scripts para objetos desarrollado por Netscape que se utiliza en millones de páginas web y aplicaciones de servidor en todo el mundo.</span></span> <span class="goog-gtc-unit" id="goog-gtc-unit-3"><span class="goog-gtc-translatable goog-gtc-from-human" dir="ltr">JavaScript de Netscape es un superconjunto del lenguaje de scripts estándar de la edición de ECMA-262 3</span></span> (<a href="/en/ECMAScript" title="en/ECMAScript">ECMAScript</a>) <span class="goog-gtc-unit" id="goog-gtc-unit-3"><span class="goog-gtc-translatable goog-gtc-from-human" dir="ltr">que presenta sólo leves diferencias respecto a la norma publicada.</span></span> <span class="goog-gtc-unit" id="goog-gtc-unit-4"><span class="goog-gtc-translatable goog-gtc-from-human" dir="ltr">Contrariamente a la falsa idea popular, JavaScript no es "Java interpretativo"</span></span>.</p>
<p><span class="goog-gtc-unit" id="goog-gtc-unit-4"><span class="goog-gtc-translatable goog-gtc-from-human" dir="ltr">Contrariamente a la falsa idea popular, JavaScript no es "Java interpretativo".</span></span> <span class="goog-gtc-unit" id="goog-gtc-unit-5"><span class="goog-gtc-translatable goog-gtc-from-human" dir="ltr">En pocas palabras, JavaScript es un lenguaje de programación dinámico que es compatible con <a href="/en/JavaScript/Guide/Details_of_the_Object_Model#Class-Based_vs._Prototype-Based_Languages" title="en/JavaScript/Guide/Details_of_the_Object_Model#Class-Based_vs._Prototype-Based_Languages">prototipos basados</a> en la construcción de objetos.</span></span> <span class="goog-gtc-unit" id="goog-gtc-unit-6"><span class="goog-gtc-translatable goog-gtc-from-human" dir="ltr">La sintaxis básica es similar a Java y C + + con la intención de reducir el número de nuevos conceptos necesarios para aprender el lenguaje. </span></span>Language constructs, such as if statements, for and while loops, and switch and try ... catch blocks function the same as in these languages (or nearly so.)</p>
<p>JavaScript can function as both a <a class="external" href="http://www.instantweb.com/~foldoc/foldoc.cgi?query=procedural&amp;action=Search">procedural</a> and an <a class="external" href="http://www.instantweb.com/~foldoc/foldoc.cgi?query=object+oriented&amp;action=Search">object oriented language</a>. Objects are created programmatically in JavaScript, by attaching methods and properties to otherwise empty objects <strong>at run time</strong>, as opposed to the syntactic class definitions common in compiled languages like C++ and Java. Once an object has been constructed it can be used as a blueprint (or prototype) for creating similar objects.</p>
<p>JavaScript's dynamic capabilities include runtime object construction, variable parameter lists, function variables, dynamic script creation (via <code><a href="/en/JavaScript/Reference/Global_Objects/eval" title="en/Core_JavaScript_1.5_Reference/Global_Functions/eval">eval</a></code>), object introspection (via <code>for ... in</code>), and source code recovery (JavaScript programs can decompile function bodies back into their source text)</p>
<p>Intrinsic objects are <code>Number</code>, <code>String</code>, <code>Boolean</code>, <code>Date</code>, <code>RegExp</code>, and <code>Math</code>.</p>
<p>For a more in depth discussion of JavaScript programming follow the <a href="#JavaScript_resources">JavaScript resources</a> links below.</p>
<h3 name="What_JavaScript_implementations_are_available.3F">What JavaScript implementations are available?</h3>
<p>mozilla.org hosts two JavaScript implementations. The first <strong>ever</strong> JavaScript was created by Brendan Eich at Netscape, and has since been updated (in JavaScript 1.5) to conform to ECMA-262 Edition 3. This engine, code named <a href="/en/SpiderMonkey" title="en/SpiderMonkey">SpiderMonkey</a>, is implemented in C. The <a href="/en/Rhino" title="en/Rhino">Rhino</a> engine, created primarily by Norris Boyd (also at Netscape) is a JavaScript implementation in Java. Like SpiderMonkey, Rhino is ECMA-262 Edition 3 compliant.</p>
<p>Each mozilla.org JavaScript engine exposes a public API applications can call on for JavaScript support. By far, the most common host environment for JavaScript is web browsers. Web browsers typically use the public API to create 'host objects' responsible for reflecting the <a class="external" href="http://www.w3.org/DOM/">DOM</a> into JavaScript.</p>
<p>Another common application for JavaScript is as a (web) server side scripting language. A JavaScript web server would expose host objects representing a HTTP request and response objects, which could then be manipulated by a JavaScript program to dynamically generate web pages.</p>
<p>For more information on embedding JavaScript in your own applications, follow either the SpiderMonkey or Rhino links below, or visit us on the netscape.public.mozilla.jseng newsgroup.</p>
<h3 name="JavaScript_resources">JavaScript resources</h3>
<dl> <dt><a href="/en/SpiderMonkey" title="en/SpiderMonkey">SpiderMonkey</a></dt> <dd>Information specific to JavaScript in C engine (aka SpiderMonkey) embedding.</dd>
</dl>
<dl> <dt><a href="/en/Rhino" title="en/Rhino">Rhino</a></dt> <dd>Information specific to the JavaScript implementation written in Java (aka Rhino).</dd>
</dl>
<dl> <dt><a href="/en/JavaScript/Language_Resources" title="en/JavaScript_Language_Resources">Language resources</a></dt> <dd>Pointers to published JavaScript standards, LiveConnect documents, and work on JavaScript 2.0.</dd>
</dl>
<dl> <dt><a href="/en/Tamarin" title="en/Tamarin">Tamarin Project</a></dt> <dd>Information on the the high-performance, open-source virtual machine for JavaScript 2.0.</dd>
</dl>
<dl> <dt><a href="/en/JavaScript/A_re-introduction_to_JavaScript" title="en/A_re-introduction_to_JavaScript">A re-introduction to JavaScript</a></dt> <dd><a href="/en/JavaScript/Guide" title="en/Core_JavaScript_1.5_Guide">Core JavaScript 1.5 Guide</a> and <a href="/En/Core_JavaScript_1.5_Reference" title="en/Core_JavaScript_1.5_Reference">Core JavaScript 1.5 Reference</a></dd>
</dl>
<dl> <dt><a class="external" href="http://www.mozilla.org/js/scripting/">Scripting resources</a></dt> <dd>Pointers to JavaScript scripting resources, including recommended reading, online references and tutorials, and sample code.</dd>
</dl>
<dl> <dt><a class="external" href="http://www.mozilla.org/js/projects.html">Projects page</a></dt> <dd>Lists other projects using the open source JavaScript engines.</dd>
</dl>
<dl> <dt><a class="external" href="http://www.mozilla.org/js/tests/library.html">Test library page</a></dt> <dd>Information about the core JavaScript test suite.</dd>
</dl>
<dl> <dt><a class="external" href="http://groups.google.com/group/mozilla.dev.tech.js-engine">mozilla.dev.tech.js-engine</a></dt> <dd>The newsgroup for discussion about the <strong>JavaScript engines</strong>.</dd> <dt><a class="external" href="http://groups.google.com/group/comp.lang.javascript/topics/" title="http://groups.google.com/group/comp.lang.javascript/topics/">comp.lang.javascript</a></dt> <dd>The newsgroup for general discussion about ECMAScript, mostly (though not necessarily) as it pertains to browsers.</dd>
</dl>
<p>JavaScript is a trademark or registered trademark of Sun Microsystems, Inc. in the U.S. and other countries.</p>
<p>{{ languages( { "en":"en/JavaScript/About_JavaScript"} ) }}</p>
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