ECMAScript 6 compatibility table
V8
ECMAScript 6 compatibility table | V8 | |
---|---|---|
33 | 55 | |
4,406 | 22,671 | |
0.1% | 0.6% | |
5.2 | 9.9 | |
14 days ago | 5 days ago | |
HTML | C++ | |
GNU General Public License v3.0 or later | GNU General Public License v3.0 or later |
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
ECMAScript 6 compatibility table
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TypeScript Is Surprisingly OK for Compilers
http://kangax.github.io/compat-table/es6/
This page lists features from es6 (and newer versions linked at the top) along with compliance to the spec. First column is the current browser, second is babel+corejs polyfills.
Overall, babel gets about 70% of the way there.
- Яндекс Браузер не переводит видео про обучение украинских танкистов, хотя другие видео с канала МО Британии переводит нормально
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Brett Slatkin: Why am I building a new functional programming language?
Case in point: Tail Call Optimization has been part of the JS spec since ES6, but remains completely unimplemented in all mainstream browsers/engines besides Safari[1]. For all but the most predictable inputs, you're pretty much forced to use loops where recursion would otherwise be preferable.
Additional case in point: async Iterables cannot be processed as a piped stream. You must use the for await construct, which is a shame considering the FP niceties that the Array type already provides for more traditional lists. Once again, you are forced to use an imperative construct unless you specifically want to defeat the purpose of using an Iterable in the first place by trying to convert it into an Array (... and potentially choking in the process, I might add!).
[1]: https://kangax.github.io/compat-table/es6/
- [AskJS] Is there a detailed comparison chart that shows what's supported in JavaScript ES5 versus ES6?
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A single developer has been maintaining core.js with little recognition or support. Almost all modern single page apps use core.js. Millions of downloads and hardly any compensation
Eventually the browsers started racing to near-full ES6 compatibility. I remember following ES6 progress in realtime with articles and with compatibility tables http://kangax.github.io/compat-table/es6/ . But many people are acting like that either didn't happen, or like it was a one and done thing (despite the ESNext naming shift to avoid the focus on numbers). So we see people just hand-waving away the importance of polyfills like in this gem:
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Tell HN: Firefox Is an awesome browser right now
> https://kangax.github.io/compat-table/es6/
Oh man this was a rough one both for FF and Chrome but Chrome did perform better slightly on cursory glance.
Thanks for providing these links, they're definitely a good rule of thumb benchmarks to test new browsers
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My 1st website "Claw Man" written in javascript
Javascript / CSS language syntax: can see availability for Javascript here - https://kangax.github.io/compat-table/es6/
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Is there any legitimate reasons for the javascript hate?
I say this as a JS user, but there is no singular JavaScript (realistically, it's not even JavaScript but instead ECMAScript). There is no one place to go that lays out all of what the language can or can't do the way PHP and Python do. The ECMAScript board makes recommendations, then the browsers and runtimes implement features of the recommendations. This site does a good job laying out which features are implemented for browsers and runtimes based on the flavor of the ECMAScript standard. This unique experience can be especially frustrating for someone learning JavaScript and coming from another language that does not have this problem.
- JS Polyfills - Part 1
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[AskJS] Is there a JavaScript library that will test all ES features on your browser and tell you which it supports and which it doesn't?
https://kangax.github.io/compat-table/es6/ has a column for "current browser"
V8
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Boehm Garbage Collector
https://chromium.googlesource.com/v8/v8.git/+/HEAD/include/c...
Due to the nature of web engine workloads migrating objects to being GC'd isn't performance negative (as most people would expect). With care it can often end up performance positive.
There are a few tricks that Oilpan can apply. Concurrent tracing helps a lot (e.g. instead of incrementing/decrementing refs, you can trace on a different thread), in addition when destructing objects, the destructors typically become trivial meaning the object can just be dropped from memory. Both these free up main thread time. (The tradeoff with concurrent tracing is that you need atomic barriers when assigning pointers which needs care).
This is on top of the safey improvements you gain from being GC'd vs. smart pointers, etc.
One major tradeoff that UAF bugs become more difficult to fix, as you are just accessing objects which "should" be dead.
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The Everything NPM Package
> If that standard library would be written in JS, a new browser (or rather a new JS engine being a part of the browser) could just use some existing implementation
That sounds great, but I'm doubtful of the simplicity behind this approach.
If my understanding is correct, v8 has transitioned to C++[0] and Torque[1] code to implement the standard library, as opposed to running hard-coded JavaScript on setting up a new context.
I suspect this decision was made as a performance optimization, as there would obviously be a non-zero cost to parsing arbitrary JavaScript. Therefore, I doubt a JavaScript-based standard library would be an acceptable solution here.
[0]: https://github.com/v8/v8/tree/main/src/runtime
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C++23: Removing garbage collection support
C++ lets you write anything you can imagine, and the language features and standard library often facilitate that. The committee espouses the view that they want to provide many "zero [runtime] cost," abstractions. Anybody can contribute to the language, although the committee process is often slow and can be political, each release the surface area and capability of the language gets larger.
I believe Hazard Pointers are slated for C++26, and these will add a form "free later, but not quite garbage collection" to the language. There was a talk this year about using hazard pointers to implement a much faster std::shared_ptr.
It's a language with incredible depth because so many different paradigms have been implemented in it, but also has many pitfalls for new and old users because there are many different ways of solving the same problem.
I feel that in C++, more than any other language, you need to know the actual implementation under the hood to use it effectively. This means knowing not just what the language specifies, but can occaissionally require knowing what GCC or Clang generate on your particular hardware.
Many garbage collected languages are written in or have parts of their implementations in C++. See JS (https://github.com/v8/v8)and Java GC (https://github.com/openjdk/jdk/tree/36de19d4622e38b6c00644b0...)
I am not an expert on Java (or C++), so if someone knows better or can add more please correct me.
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Abstract Syntax Trees and Practical Applications in JavaScript
Remember that we earlier established that every source gets parsed into an AST at some point before it gets compiled or interpreted. For example, platforms like Nodejs and chromium-based browsers use Gooogle's V8 engine behind the scenes to run JavaScript and of course, some AST parsing is always involved before the interpreter kicks in. I looked V8's source and I discovered it uses its own internal parser to achieve this.
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Notes: Advanced Node.js Concepts by Stephen Grider
In the source code of the Node.js opensource project, lib folder contains JavaScript code, mostly wrappers over C++ and function definitions. On the contrary, src folder contains C++ implementations of the functions, which pulls dependencies from the V8 project, the libuv project, the zlib project, the llhttp project, and many more - which are all placed at the deps folder.
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What does the code look like for built-in functions?
Here is the implementation of of Array. prototype.map in V8. It's written in a language called Torque which appears to be a special language just for the v8 engine.
- What's happening with JavaScript Array References under the hood?
- FAMILIA PQ NAO TEM VAGA EM C E C++ NESSE MERCADO **********?????
- [AskJS] Do you have to be a natural talent to reach deep knowledge?
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is there any resource for JavaScript that explain what kind of logic statement behind each function and why it's give this output and only accept this input etc... ?
It sounds like you want to know how JavaScript is implemented in the browser. The thing is, there is no universal implementation for JavaScript. JavaScript defines a specification that must be adhered to, and then each browser vendor can implement it in whatever way they see fit, as long as it does the specified things. For example (and I'm not saying this is the case) it's entirely possible for Chrome to implement Array.sort() using merge sort, while Firefox implements it as quick sort. You can try to find the source code for the implementation in a certain browser, but that will not be universal. I imagine you can find out how it works in Chrome somewhere in https://chromium.googlesource.com/v8/v8.git, though I'm not sure exactly where.
What are some alternatives?
es6-features - ECMAScript 6: Feature Overview & Comparison
Duktape - Duktape - embeddable Javascript engine with a focus on portability and compact footprint
Babel (Formerly 6to5) - 🐠 Babel is a compiler for writing next generation JavaScript.
ChakraCore - ChakraCore is an open source Javascript engine with a C API. [Moved to: https://github.com/chakra-core/ChakraCore]
Traceur compiler - Traceur is a JavaScript.next-to-JavaScript-of-today compiler
Lua - Lua is a powerful, efficient, lightweight, embeddable scripting language. It supports procedural programming, object-oriented programming, functional programming, data-driven programming, and data description.
es6-cheatsheet - ES2015 [ES6] cheatsheet containing tips, tricks, best practices and code snippets
V7 - Embedded JavaScript engine for C/C++
es6features - Overview of ECMAScript 6 features
ChaiScript - Embedded Scripting Language Designed for C++
Lebab - Turn your ES5 code into readable ES6. Lebab does the opposite of what Babel does.
Cython - The most widely used Python to C compiler