ECMAScript interpreter for Cython & Python built for
- Solving & Decrypting Annoying Puzzles and Captchas at immense speeds.
- Calling upon different Javascript libraries Examples might include:
- llparse (Even though I maintain a python version but you could easily call upon llparse from javascript using this extension)
- yt-dlp-ejs (Decrypting challenges might take a while but that was why I wrote this library so we could start optimizing these things )
- Being tiny and easy to use
- Having ECMA6 Support
- Having a maintained backend (QuickJS-NG)
- Being a good companion alongside selectolax or beautiful-soup the choice is yours...
- License friendly, after abandoning pyduktape due to the backend no longer being maintained but also having a pretty poor license all together, It inspired me to try something new for a change that could run newer HTML5 Javascript for any puzzle that is thrown your way.
Installation of cyjs is pretty simplistic and you can get the released version from pypi
pip install cyjs
If your planning to contribute or want in on anything newly added you can clone the github repo there is however one dependency needed which is CMake, it was chosen to keep the setuptools section cleansed and allow the quickjs-ng contributors to help us with those sections. You can install cmake using pip if you need something lazy and quick. It's recommended you install cmake globally if you don't have it yet.
pip install cmake
After getting cmake it is recommended to use uv to build and install the cyjs library in development mode
uv sync
Otherwise you can try this approch know that you need pytest if your planning to test anything locally.
uv venv
uv pip install -e .
pip install -e .
from cyjs import Context, Runtime
def main():
# You can also provide a runtime if needed it's usage before making multiple contexts however
# is completely optional
rt = Runtime()
ctx = Context(rt)
ctx.eval("function add(a, b){ return a + b; }; globalThis.add = add;")
add_func = ctx.get_global().get("add")
# 3
print(add_func(1, 2))
if __name__ == "__main__":
main()Example of use with external html parser tools.
from cyjs import Context
from selectolax.lexbor import LexborHTMLParser
# This example demonstates ways of cracking javascript out of webpages
# with an expernal HTML Parser and cyjs to handle the javascript logic.
# Know that A True HTML5 Dom-API Might require you to make your own
# functions and imagination but also reverse engineering the target page.
HTML_PAGE = b"""
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<div class="captcha">
<script>
function fake_captcha(name) {
return name + "-key";
}
</script>
<!-- Use your imagination a little... -->
</div>
<div>
<script>
this.captcha = fake_captcha('123')
</script>
</div>
</body>
</html>
"""
def main():
html = LexborHTMLParser(HTML_PAGE)
captcha = html.css_first("div.captcha > script").text(strip=True)
fake_solver = Context()
fake_solver.eval(captcha + "\nglobalThis.fake_captcha = fake_captcha;")
result = fake_solver.get_global().invoke("fake_captcha", "123")
# should print
# "123-key"
print(result)
if __name__ == "__main__":
main()There will be more examples in a future update.
| Library | ECMA-6 Support | Size | Performance | Typestubs And Readability | Cython cimportable |
|---|---|---|---|---|---|
| js2py | has to translate ECMA6 to 5 | Medium | Decent at ECMA5 and html5 scripts that use Emca-5 but starts suffering when trying to do ECMA-6 | Lacks proper typehinting making everything into an unwanted guessing game | No and it's pure python |
| quickjs (python library) | Yes | Small | Has to convert some objects back and forth but lacks typestubs and documentation | Lacks typestubs | CPython Extension that could've used a C-API Capsule to help it gain a bit of lubricant with other projects. |
| pyduktape | No | Small | somewhat fast but the backend is unmaintained and lacks proper type-hinting | None | Impossible |
| pyduktape2 | No | Small | somewhat fast but the backend is unmaintained and lacks proper type-hinting | Because this one didn't have that and my pull requests kept being laid dormant I wrote pyduktape3 | can't be done |
| pyduktape3 | No | Small | Very fast but the backend made by me but the C backend is unmaintained which is why the project was soon abandoned in favor of cyjs | I did add typestubs to this library. | The Last cherry on top this was cimporting pyducktape3 |
| strv8 | I haven't tried this one yet (Might be due to lack of windows support but I don't remeber) | Large due to V8 | Probably very fast becuase v8 is built by google. | I don't know, I sure hope a project like this has that. | I haven't seen the sourcecode yet... |
There's a few things I didn't get to becuase they are more or less puzzles to implement than they need to be but if anybody can figure these out feel free to fork and send a pull request along with a test added to pytest for eatch to ensure it works correctly. I may be uploading this library to pypi after the other things are implemented but these seem more of a chore for me to solve than really anything else.
-
If anybody finds a smarter approch to anything that has already been written throw me an issue or pull request.
-
Reporting and fixing bugs.
-
JSClass cdef class extension that can be subclassed in python and cython along with the hooks for all the JSClassExoticMethods (we need an approch to passing off a cdef class as an opaque value which I have not figured out how to do yet)
- JSClassFinalizer Hook
- JSClassGCMark Hook
- A safe approch for handling JSClass to python object conversion and vice versa (if possible)