EcmaScript (JavaScript) 5 aprovado

9 de dezembro de 2009 5 respostas

Rafael_Afonso 9 de dezembro de 2009

JavaHispano:

Aprobada la quinta edición de ECMAScript, una nueva especificación para JavaScript

La semana pasada fue aprobada la quinta edición de ECMAScript [size=9](vejam texto abaixo)[/size] (ECMA-262 5th edition), una nueva especificación para JavaScript. Se trata de la primera revisión mayor de la especificación del lenguaje JavaScript desde 1999. De las 21 partes con derecho a voto, sólo IBM votó en contra por la falta de soporte para operaciones con decimales, e Intel se abstuvo. Ahora, el próximo paso en la estandarización de la próxima versión de este lenguaje es enviar la especificación ha ISO, para que también sea aprobada por este organismo.

Con esto se rompe finalmente el atasco de la cuarta especificación de JavaScript, que debía haberse terminado en 2008, y que nunca llegó a convertirse en un estándar por falta de acuerdo entre las distintas partes.

Las dos novedades que más atrae mi atención en nueva especificación son el soporte para JSON y la posibilidad de “congelar” un objeto, impidiendo que sea modificado, mediante Object.seal() y Object.freeze(). Esta última característica sin duda será un pilar para reforzar la seguridad del lenguaje.

Aquí tenéis el PDF con la nueva especificación.

Fonte: http://www.javahispano.org/contenidos/es/aprobada_la_quinta_edicion_de_ecmascript__una_nueva_especificacion_para_javascript/

Fonte: https://mail.mozilla.org/pipermail/es-discuss/2009-December/010215.html

Resta saber quando os browsers o implementarão. E finalmente tomaram vergonha na cara e criaram um método trim() para String.

5 Respostas

Rafael_Afonso 9 de dez. de 2009

Mais uma nota:

Mitch Pronschinske:

New Standard for JavaScript After Years of Disagreement

After ten years with no major revision, the European Computer Manufacturers Association (ECMA) general assembly recently approved the ECMA-262 5th edition (ES5) spec as the ECMAScript standard. JavaScript, JScript, and ActionScript are the well-known dialects of ECMAScript.

The spec passed by a vote of 19 to 2, receiving less criticism than the unstandardized 4th edition. Only IBM and Intel voted against the proposal. IBM voted against the spec because of the lack of decimal and Intel didn’t have enough time to look over the intellectual property implications. The next step for the ECMA will be to submit the ES5 spec to the International Organization for Standardization (ISO).

The new standard now includes JavaScript Object Notation (JSON) as a component of ECMAScript. Objects in the new ECMAScript can be shielded from manipulation with Object.seal() and Object.freeze(). The interpreter will now enforce tougher rules in “use strict” mode. Undeclared variables, for example, will not be executed.

Progress for ECMAScript has been hindered by disagreements and controversy over the last few years. The fourth edition of ECMA-262, originally targeted for completion by October 2008, would have been the first major update to ECMAScript since the third edition became standard in 1999. The fourth edition was derailed when a debate between Chris Wilson, Microsoft’s platform architect for Internet Explorer, and Brendan Eich, the creator of JavaScript who is now the CTO for Mozilla, surfaced on multiple blogs. Wilson said that the backwards incompatibility of EC4 would result in “breaking the Web,” while Eich gave examples of why that wouldn’t happen.

As a result, Microsoft, Yahoo, and other opponents of EC4 formed their own camp to design a smaller update for ECMAScript 3 initially called ECMAScript 3.1. The two camps tried to develop their specs in parallel but differing philosophies kept both specs from being standardized for over a year. The two teams finally reached a compromise in August 2008: the ECMA Technical Committee 39 (TC39) would focus on ECMAScript 3.1, renamed edition 5. The recent approval of the EC5 spec is the fruition of many years of obstacles and compromise.

The fourth edition is not dead yet though. In 2008, the project was renamed ECMAScript Harmony and will be more modest than the previous EC4 proposal. The spec will include syntactic extensions but won’t include several packages, namespaces, and early binding from ECMAScript 4. Harmony might be renamed ECMAScript 6th edition now that the 5th edition is the most recent standard.

Fonte: http://css.dzone.com/news/new-standard-javascript-after

:?: Quando diz “Undeclared variables, for example, will not be executed.” significa então que todas as variáveis deverão ser declaradas com “var”? Devo ler melhor a específicação.