in ECMAScript

ECMA-262-5 in detail. Chapter 0. Introduction.

We have finished analysis of the most important parts and theoretical aspects concerning 3rd edition of the ECMA-262 specification, i.e. standard devoted ECMAScript programming language. We have done and achieved a lot. Originally written in Russian, this series after more than half an year has been translated to several languages, what allowed this information to be shared with JavaScript developers and with everyone who interested in deep ECMAScript allover the world.

Today when the 5th edition is released it is time to start analysis of this new version of the specification. At the moment it still isn’t implemented widely in the complete view, although there are already many implementations which have the new functionality — at least partly.

As we know ECMAScript 4 (aka JavaScript 2.0) with concept of classes has been canceled. Instead the new version is improved version of the ECMA-262-3 and is called as ECMAScript 5. For shortness we will use ES5 concept and comparing with 3rd edition corresponding — ES3.

I thought how to manage the new series and descriptions of related chapters in the most convenient way. On one hand, it is the new standard which could deserve complete separate series with all chapters. But then many of them will repeat descriptions of ES3 series. On the other hand, as we mentioned, the 5th edition is just the improvement of the previous 3rd version — without completely new and innovating approach. We can treat ES5 as an extension of the ES3. And from this viewpoint many already discussed aspects are the same as for the ECMA-262-3. Nevertheless, some concepts of ECMA-262-5 have new terminology and implementation. And exactly these new details are the most interesting for us.

Taking into account this fact, I decided to explain separately only these distinctions and with referencing to corresponding chapters of the ECMA-262-3 series. Moreover, ES3 still rocks (and will until web-developers support some old browsers; although, I am sure that will be made some acceptable shims to imitate ES5 approach using ES3) and from this point of view understanding how works ES3 is also important and useful. So for those who will start learning of ECMAScript from this new ECMA-262-5 series, every chapter will contain sort of dependencies list, i.e. chapters of ECMA-262-3 series which should be already read for complete understanding of the current chapter.

To whom this series is recommended:

As before, first of all for those who want to learn JavaScript deeply and professionally — at theoretical level of the specification. Level of explanation still will be academical, which means we won’t use some simplified terminology without subtleties for the basic (but as usually is — superficial) understanding of the ECMAScript nature. Also this series isn’t a practical “copy-paste” solutions resource and not the textbook for novices. Therefore it is desirable to have already some experience in ECMAScript and programming as a whole. And for beginners I recommend to read first the basic articles on JavaScript, to understand the language in general, and then, if there will be an interest, to return to more detailed ECMAScript studying.

Dmitry Soshnikov

Chapters of the series:

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  1. Great!
    ECMA-262-3 articles were amazing, I cannot wait for the new one!


  2. Well, it has not been a norm for me to post comments, your articles have been very great. And for a little confession i downloaded all pages on ECMA-262-3 and spiral binded them into a book which have been studying day & night. Am still a wannabe but with my going study and materials am su h of the future thanks bud.