Infrequently Noted

As outlined by JQuery lead John Resig in this post, it's hard not to notice how much Dojo's query engine stomps on the the competition on current browsers. Dojo will load even quicker when we're able to remove the XPath branch in the query engine which is currently only being kept on life support for the benefit of Firefox. The rest of Dojo has been designed with the same eye to real-world performance factors in mind, hence the build and package systems which help you implement Steve Souders' performance recommendations gradually, without major code changes.

Regardless of how good it feels to see our numbers recognized for all the hard work that has gone into the Dojo design, I think it's also good to keep them in perspective. Most of the available query engines are "fast enough" – although there's really no reason why your query engine of choice should be twice as slow as Dojo's, given that ours is 100-point Open Source. Having a native implementation is nice, but the primary benefit now is in reducing the number of bytes we need to send on the wire, not in actual query speed advantages. Making queries faster isn't in the critical path for improving the real-world performance of any Dojo apps I know of, and I bet the same is true for JQuery users. Reducing the size of the libraries, on the other hand, is still important. Now that we're all fast enough, it's time that we stopped beating on this particular drum lest we lose the plot and the JavaScript community continue to subject itself to endless rounds of benchmarketing.

There still seems to be an amazing amount of FUD going around regarding the Harmony announcement. There is clearly a very different perspective from those who have been sitting inside the WG for the past year (as Kris Zyp and I have been lucky to). Inside the WG, the change seems a welcome way to break a logjam of reasonably held opinions of people who are all acting in good faith. From the outside, it all looks like confusion and game-playing.

One of the things, though, that keeps getting me frustrated as I read the "coverage" is that the names people use are confused. Probably because the names are confusing. Here's a quick glossary:

ECMAScript 3

Aka: "JavaScript", "ES3", "ECMAScript 262-3", and "JScript".

The current JavaScript that every browser implements (more or less). This is the current ratified standard and represents the 3rd edition of the ECMAScript spec. It is very old. Nothing else in this list is (yet) a ratified standard of any sort.

ECMAScript 4

Aka: "ES4", "JavaScript 2"

A new language which was to be mostly backwards compatible but add optional (gradual) typing and class-based inheritance. Based loosely on Adobe's ActionScript 3. This is the language effort which died as a result of Harmony.

ECMAScript 3.1

Aka: "ES3.1"

A set of small additions to ES3. Working drafts are available and will likely go to the standards process with few changes. Planning for this edition was started at Microsoft and Yahoo's behest late last year, causing the split in the working group which has been healed by the Harmony announcement.

ActionScript 3

Aka: "AS3"

Adobe's current JavaScript-like language, only with many features lifted from languages like Java which also enforce types and class-based semantics. This was the starting point for much of the work which became known as ES4.

Tamarin

A JIT-ing byte-code virtual machine (VM) which is at the core of the Flash Player and was donated by Adobe to the Mozilla Foundation. This is the VM that runs ActionScript 3 code today but will likely run "real" JavaScript for Mozilla in the future. It is not a full implementation of ES3 or ES4, but instead implements its own byte-code and needs to be wedded to a "front end" (like the ActionScript 3 compiler from Adobe) in order to be usable by programmers.

Tamarin-tracing

A VM which implements the same byte-code language as Tamarin (known as "ABC") but which is designed for use in mobile devices and other scenarios where code size and VM footprint are important. It implements trace-tree JIT-ing as a way to speed up hot-spots. Also donated to Mozilla by Adobe.

TC39

The name of the ECMA technical committee which is chartered to evolve the JavaScript language.

Harmony

A new code-name for a language which is to come after ES3.1. It will feature many of the things ES4 was trying to accomplish, but may attempt them from different directions and will focus much more on incremental, step-wise evolution of the language.

JavaScript 2

A now-defunct name. This name was originally given to Waldemar Horwat's first proposal at a large-scale evolution of the JavaScript language in 1999. That effort did not succeed (although Microsoft implemented some of it in JScript.NET) and subsequent work via the current TC39 charter to build ES4 has sometimes been given the name "JavaScript 2", but it never really stuck. Not a name that describes any ratified standard or current proposal.

ECMAScript

The formalized name of the JavaScript language. Since Sun Microsystems owns the name JavaScript and has no idea what to do with the trademark (but has been benevolent thus far), the ECMA committee which standardized the language was forced to adopt a different name.