W3Conf 2013

El EcmaScript que viene: los detalles de ES6

Kit Cambridge  · 


Extracto de la transcripción automática del vídeo realizada por YouTube.

so thanks so much for that amazing introduction Divya it really is a pleasure to be here speaking with you today so before it get started just a quick poll first of all how many of you have heard of one new feature in the latest version of Atma script equi

script six okay excellent so good mix how many of you conversely don't know what ECMO script is at all okay ready so won't be completely redundant while I explain so please bear with me all your questions will be answered so let's go ahead and

get started talking about the next revision of the language as I'm sure I'm sure some of you may have heard there is a new there there is a new revision of the language that is being currently prepared and worked on by a working group in a committee

that revision is called acma script 6 and it brings along some much-needed syntactic conveniences and api's to the exhibit to existing JavaScript code one of the things that fascinates me most about technology is that every technology has a story behind

it and equus crypt 6 is no exception but like in any good story it's not just comprised of the prime of the primer protagonists or any earth-shattering situations in any in any good narrative there are a lot of different aspects and their and oftentimes

it's the supporting characters or the amalgam of various individual situations that might not seem to be particularly earth-shattering on their own but when combined actually create a significant influence sorry about that back okay so in this presentation

I'll not only hope to talk to you a bit about the new features in equus curve six but also tell you a bit about the story so without further ado let's begin our story begins as these stories often do with an up-and-coming engineer at Netscape Communications

Corporation in 1995 this particular engineer is tasked with writing a client-side scripting language to compliment and capitalize upon the Java craze that was occurring at the time in 10 days he conceives a language called mocha which is then changed to live

script and then hardly changed javascript before shipping in the latest and greatest browser at the time Netscape Navigator two point O now javaScript Leah clips its distant and rather confusingly named cousin and is implemented by Microsoft under the name

of jscript and then integrated into its browser at the time I III shortly thereafter Netscape submitted JavaScript to the ECMA the European computing Manufacturers Association which was then distilled into the trade name of acma script the creator of JavaScript

bread and Ike has been known to comment more than once that the trade name of acma script was never particularly well received by anyone in fact it sounded very much like a skin disease but nonetheless it was the name that was selected for the language so

this you can think of as the standardized version of JavaScript what we colloquially referred to as javascript is actually one of several implementations of the ACMA script standard whereas JavaScript itself when used as a trademark is actually owned by oracle

and licensed by mozilla its name that mozilla uses for its specific javascript implementation that's present in firefox thunderbird and sea monkey so it's an interesting so JavaScript history is not only intriguing in its syntactic development but

also the naming from the very beginning it needed to share a name with its distant cousin and then adopt a series of various names and implementation engines so JavaScript and jscript were back in nineteen ninety six at the time continued to diverge from the

parent specification and shortly thereafter the ECMA released a second draft that was primarily targeted at bringing javascript or acma script rather in line with existing international standards but it wasn't until 1999 that the third edition of the language

really took off with the third edition iveco script it introduced features that today we would consider absolutely absolutely essential to to programming things like regular expressions additional string methods new control statements like switch and do-while

new operators like in an instance of exception handling tighter error semantics and features for numeric formatting and other international changes now at this time because javis carpet experience such a surge of popularity we were the specification was built

such that it would anticipate future growth with a follow-up fourth edition it was a fantastic time to be to begin standardizing language but alas the fourth edition was not quite meant to be in 2005 the technical committee responsible for moving the language

Ford tc39 released a draft of the ACMA script for specification and looking at it you and comparing it to the specification responsible for the third edition it's very difficult to see any resemblance between them the echo script for draft inherited several

inherited several features from divergent implementations like ActionScript so interesting of what Adobe did with actionscript was to start with the base of acma strip three and then extended with additional semantics like say static type checking classes

packages namespaces and even conveniences like block scoping generators and rest parameters and so you can look at es for as an attempt to take those new to take those syntactic additions and integrate them back upstream into the specification but unfortunately

there was a general consensus that es for lacked focus and that was becoming an incredibly backward incompatible revision of language and normally working with Jen normally iterating JavaScript might not have presented such a significant concern after all

the try-catch statement was introduced in es3 in 1999 so took a few years before all implementations could before developers could use them in every implementation successfully but it was also in 2005 that Jesse James Garrett had coined term Ajax launching

the and launched the Ajax evolution suddenly companies and web developers were able to build complex highly dynamic applications using a scripting language that had been that had last been modified and had seen a significant revision in 1999 so the and there

was there was great concern that the 4th edition of the specification would end up breaking the web now javaScript as a language is very unique because the barrier to entries to it is so low every almost every browser on the planet ships with some form of

JavaScript engine and today experimenting with it and even beginning to write your own programs have never been easier in fact with the multitude of dev tools that are shipping in modern browsers all it takes to start writing and learning so in 2005 browsers

had not yet become as sophisticated but nonetheless backward compatibility was a concern so it was with perhaps not too much reluctance that tc39 the technical committee decided to shell the draft of yes for and create an implementation called acma skirt five

today if you look on on the ECM I website you'll see a list of historical specs but interesting enough ps4 is nowhere to be found that's because the specification never reached any status beyond a basic draft instead tc39 you regrouped and released

a version of Equus crib called Equus court five in 2009 now compared to the difference between es 3 and es for the revisions were primarily conservative it tightened down some semantics around regular expressions eval and global objects it added some new object

reflection methods like object get prototype of define properties and even object I create it added the array extras that Mozilla had implemented in Firefox to about 23 years earlier it added strict mode and native JSON support and it's only syntactic

extension where getters and setters so under the hood though atmosphere 5 represented a significant undertaking to revamp the internals of the language and it's upon these successes that the next version of the language echo script 6 builds so here we

are in 2013 with a specification slated for completion before the end of the year and we've come full circle if atmosphere 5 was a conservative change es6 is is showy and flashy there are many different features available from New clap from class syntax

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