V7 VS V8

Compare V7 vs V8 and see what are their differences.


Embedded JavaScript engine for C/C++ (by cesanta)
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V7 V8
3 55
1,401 22,394
0.4% 1.2%
1.8 9.1
about 3 years ago about 22 hours ago
C C++
GNU General Public License v3.0 or later GNU General Public License v3.0 or later
The number of mentions indicates the total number of mentions that we've tracked plus the number of user suggested alternatives.
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.


Posts with mentions or reviews of V7. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2023-07-02.
  • Flattening ASTs (and Other Compiler Data Structures)
    7 projects | news.ycombinator.com | 2 Jul 2023
    I used such a succinct AST structure to implement a JavaScript parser and interpreter for a severely memory constrained environment (embedded): V7 (https://github.com/cesanta/v7)

    We later switched to a ast->bytecode compilation step but for a while the implicit AST was directly traversed during interpretation.

  • Microvium Is Small
    4 projects | news.ycombinator.com | 21 Jun 2022
    Nice! A few years ago I took a stab at this problem space with https://github.com/cesanta/v7 ; with fun tricks like in-place compacting GC, stdlib JS object graph "frozen" in rom etc
  • JavaScript Is Weird
    7 projects | news.ycombinator.com | 28 Jun 2021

    Languages are not all equal nor do they all function in the same way, and that's not my opinion.

    Javascript syntax itself is one thing, and you can certainly feel free to Javascriptify some C++ libraries and make it all look a certain way for specific tasks, while managing things behind the scenes, up to a point... but there is no getting around the fact that SOMEONE and some languages are needed to implement low level systems functionality.

    the power of Cython or the Python C FFI is that it allows you to script/glue modular native code.

    You then state "C++14 may have been ratified 7 years ago but it's not the target code your build chain spits out"

    no, a C++ COMPILER spits out assembler code that then gets assembled and linked into an executable.

    The C++ or C code corresponds directly to a given set of assembler instructions which correspond directly to CPU instructions.

    You claim that Python programming of microcontrollers is mainstream, but this is not true nor possible. Python SCRIPTING of code modules (that cannot be written in Python) is certainly one way to assemble a system from pre-built legos.

    If you refer to knowing what I'm talking about as gatekeeping and egoism, might I suggest that you insist less forcefully in the correctness of incorrect things you state? we could be done with this spat in short order if YOU would refrain from speaking falsehoods. lies.untrue things.

    I look forward to your lisp c compiler. make sure that it's 100% lisp from the bottom up, or I'll consider you're having ceded my point. Consider that the lisp you author in has a garbage collection system that lisp cannot have written originally, nor has any semantics for the underlying memory structures of, but hey, I guess if one is committed to pretending that all languages are equal for all tasks, who am I to question ones self-identification with a given language.


Posts with mentions or reviews of V8. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2024-01-21.
  • Boehm Garbage Collector
    9 projects | news.ycombinator.com | 21 Jan 2024

    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.

  • The Everything NPM Package
    2 projects | news.ycombinator.com | 6 Jan 2024
    > 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

  • C++23: Removing garbage collection support
    3 projects | news.ycombinator.com | 1 Nov 2023
    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.

  • Abstract Syntax Trees and Practical Applications in JavaScript
    13 projects | dev.to | 21 Oct 2023
    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.
  • Notes: Advanced Node.js Concepts by Stephen Grider
    5 projects | dev.to | 19 Aug 2023
    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.
  • What does the code look like for built-in functions?
    2 projects | /r/learnjavascript | 13 Jun 2023
    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.
    2 projects | /r/learnjavascript | 13 Jun 2023
  • 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... ?
    2 projects | /r/learnprogramming | 12 Oct 2022
    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.
  • Minimize Heap Allocations in Node.js
    4 projects | news.ycombinator.com | 28 Sep 2022
  • [AskJS] Who first used the term "spread operator" re spread syntax ...?
    3 projects | /r/javascript | 18 Sep 2022
    chrome v8 commits referring to spread operator one of them: https://github.com/v8/v8/commit/93b3397e52d3faf38059718de335027e57b9690d

What are some alternatives?

When comparing V7 and V8 you can also consider the following projects:

Duktape - Duktape - embeddable Javascript engine with a focus on portability and compact footprint

ChakraCore - ChakraCore is an open source Javascript engine with a C API. [Moved to: https://github.com/chakra-core/ChakraCore]

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.

ChaiScript - Embedded Scripting Language Designed for C++

Cython - The most widely used Python to C compiler

Flutter - Flutter makes it easy and fast to build beautiful apps for mobile and beyond

Wren - The Wren Programming Language. Wren is a small, fast, class-based concurrent scripting language.

SWIG - SWIG is a software development tool that connects programs written in C and C++ with a variety of high-level programming languages.

sol2 - Sol3 (sol2 v3.0) - a C++ <-> Lua API wrapper with advanced features and top notch performance - is here, and it's great! Documentation:

libffi - A portable foreign-function interface library.

v8pp - Bind C++ functions and classes into V8 JavaScript engine