什么时候将在jQuery，mootools等库中构建JavaScript引擎（如Spidermonkey），并且有人可以帮助实现这一点？

Question

We all know the great benefits that js libraries such as jquery and mootools etc. have contributed to web browsers and web development. These libraries are now included in a lot if not most of all websites.

So, I was wondering why none of the current javascript engines just include these functionalities inside the javascript engine itself . No doubt this has even more benefits such as performance, no need for external loading, standardisation (and its own benefits), etc.

I realize that this would probably only benefit web browsers and alike, though there must be also many uses beyond just web browsers, but for the sake of argument, one could just add such engine built in functionalities in an optional engine / ECMASCript -and I am guessing the word here- component (with emphasis on optional), that could then be enabled or added only in the engines inside web browsers.

Does anyone know this or has more info on this all?

My second questions is: If we, the community, would decide this to be a great progress for the future, where can we propose/ask such a thing and what else can we do to make this happen?

(Some of you must realize the trouble that some feature cost to be included in some projects, such as the years to decade old feature requests voted on by zillion users and never got through because of ...well..let's not be ungrateful to developers and leave these dots for your own imagination. So I'd rather have that the community focus this wish on 1 place only nad maybe the answer to this second question is the start of it?)

Answer 1

ECMAScript only intends to standardize the minimum amount of language and support library necessary to build these higher level libraries you're describing. Also, things like jQuery work on the Document Object Model provided by the browser code, which isn't even part of the ECMAScript standard -- ECMAScript just knows about DOM nodes in the general category of "foreign objects". The SpiderMonkey engine implements just the JavaScript language and its small standard library, which is then embedded into the larger Firefox browser environment.

So, to answer the question more directly: is it possible to give the JavaScript engine intimate knowledge (and perhaps an implementation) of a user-level library like jQuery? Yes, although you'd be breaking a lot of componentization in the browser, as you mention. Will anybody actually do it? Most likely not, because JavaScript engines just implement the core of what's necessary to build higher level libraries, like jQuery. Everybody is happy with them living outside of the JS engine, and a nice property of JavaScript is that you can just load the library in as you need it -- the source is freely available.

In fact, as a further note, JS engines are doing more and more to push ECMAScript standard library code out of C++-implementation land and into something called "self-hosted builtins", which enables functions like Array.indexOf to be implemented in JavaScript itself (ie, with a for loop and comparisons). This exposes more JavaScript code to the natural process of optimizing JIT compilers, instead of having to deal specially with calls into native C++ implementation code.