[PY] Added the ability to run Brython code by Ahsoka · Pull Request #8640 · SeleniumHQ/selenium

Ahsoka · 2020-08-22T19:19:22Z

Description

For the uninitiated Brython is a way to use Python code on the front-end instead of Javascript. This pull-request adds a execute_brython() method which allows you to execute Brython code much in the same way you would use the execute_script() method to execute JavaScript code. There is also now a load_brython() method which is used to load the necessary JavaScript files to run Brython code and must be called before using the execute_brython() method.

Examples

Here are a couple of examples of using the load_brython() and execute_brython() methods.

Example 1

>>> from selenium import webdriver
>>> driver = webdriver.Chrome()
>>> # You must use `load_brython()` before using `execute_brython()`
>>> driver.load_brython()
>>> driver.execute_script("console.log('Hello World');")
>>> # Equivalent using `execute_brython()`
>>> driver.execute_brython("print('Hello World')")

Example 2

>>> from selenium import webdriver
>>> driver = webdriver.Chrome()
>>> driver.load_brython()
>>> # turtle_script is defined below
>>> driver.execute_brython(turtle_script)

This is turtle_script ⬇

# Adapted from https://brython.info/gallery/turtle.html
from browser import document, html
import turtle
if 'turtle-div' not in document:
    document <= html.DIV(Id='turtle-div', style={'float':'left', 'border': '1px solid green'})
turtle.set_defaults(
    turtle_canvas_wrapper = document['turtle-div']
)
t = turtle.Turtle()

t.width(5)

for c in ['red', '#00ff00', '#fa0', 'rgb(0,0,200)']:
    t.color(c)
    t.forward(100)
    t.left(90)

# dot() and write() do not require the pen to be down
t.penup()
t.goto(-30, -100)
t.dot(40, 'rgba(255, 0, 0, 0.5')
t.goto(30, -100)
t.dot(40, 'rgba(0, 255, 0, 0.5')
t.goto(0, -70)
t.dot(40, 'rgba(0, 0, 255, 0.5')

t.goto(0, 125)
t.color('purple')
t.write("I love Brython!", font=("Arial", 20, "normal"))


turtle.done()

Result of Example 2 ⬇

Types of changes

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to change)

Checklist

I have read the contributing document.
My change requires a change to the documentation.
I have updated the documentation accordingly.
I have added tests to cover my changes.
All new and existing tests passed.

Used to load the necessary Javascript files to run Brython code.

This method allows you to execute Brython code just like the execute_script() method allows you to execute Javascript code.

CLAassistant · 2020-08-22T19:19:28Z

All committers have signed the CLA.

… recommendations

…argument

Before the stdlib was accessed via files in the Brython Github repository, but it now accessed through the brython_stdlib.js file. Initially, I thought this method of acessing the Brython stdlib would not work because for some unknown reason, when brython_stdlib,js accessed the Indexed Database API, it caused the following error: "access to the Indexed Database API is denied in this context". However, recently I discovered in the brython() function there is an option to disable access to the database (which is used to load the Brython stdlib) and access through some other method (which I don't fully understand).

Ahsoka · 2020-08-23T00:03:54Z

I am not sure how I would go about adding documentation. I have added a docstring to both of the new methods I created. Does this satisfy the I have updated the documentation accordingly. requirement? Please let me know.

AutomatedTester

I don't mind adding support for Brython but ongoing it might break and there are no tests in this patch to make sure that never happens.

Would it not be better to have a package that you own that has a dependency on Selenium that you ship?

AutomatedTester · 2020-08-26T21:56:11Z

py/selenium/webdriver/remote/webdriver.py

            'args': converted_args})['value']

+    def load_brython(self,
+                     src="https://cdn.jsdelivr.net/npm/brython@3.8.9/brython.min.js",


Are you sure Brython users would always be in the internet? Who not bundle as data like some of the other JS packages that are shipped

I also thought of something similar to what you suggested but unfortunately it can be unreliable. For example, in Chrome whenever I try to access local files I get the follow error Not allowed to load local resource: {file name here}. However, I believe in Firefox it would work with no problem (I have not tested this but I have reason to believe this to be the case from the exhaustive amount of research I have conducted on this topic). Additionally, unless configured in a certain way, Brython has a reliance on certain external files anyway. Loading Brython from a file would still require access to the external files via the internet.

We need to use bazel here. I will help with this part.

py/selenium/webdriver/remote/webdriver.py

AutomatedTester · 2020-08-26T21:59:59Z

py/selenium/webdriver/remote/loadBrython.js

@@ -0,0 +1,4 @@
+var script = document.createElement('script')


These files should in /javascript/brython

When you refer to /javascript/brython do you mean py/selenium/webdriver/remote/javascript/brython or the top level directory /javascript/brython.

top level /javascript/brython and add a bazel file or if you want to use npm then we can add it to the package.json and I will help with the bazel stuff .

Alright I added the files to the top level directory /javascript/brython. See this commit for reference. I am not too familiar with Bazel so please let me know what I need to do to reference the files in my code.

As of now they are currently referenced like this:

See the below here.

_pkg = '.'.join(__name__.split('.')[:-1]) template = pkgutil.get_data(_pkg, 'loadBrython.js').decode('UTF-8')

and like this

_pkg = '.'.join(__name__.split('.')[:-1]) running = pkgutil.get_data(_pkg, 'runBrython.js').decode('UTF-8').format(repr(script))

See the above here.

Before this patch there was a **MAJOR BUG** that would cause an error when using the `execute_brython()` too soon after using the `load_brython()` method. Now, the `load_brython()` method will now terminate **ONLY** after Brython has been succesfully loaded.

This test tests for several things: - Can Brython be successfully loaded in a reasonable amount of time (5 seconds to be exact)? - Are the stdlib modules accesible? (this is tested by accessing the turtle module) - Is execute_brython functioning properly? (This is tested by running a simple script with turtle)

Ahsoka · 2020-08-27T21:47:19Z

I added a single test that will pretty reliable test whether or not Brython works. See these changes for reference,

Ahsoka · 2020-09-01T21:39:33Z

@AutomatedTester Whenever you get a chance please let me know what the next steps are in getting this PR ready to merge. Thank you!

The reasoning behind this is instead of constantly changing the URL everytime a newer version of Brython comes out, use a URL that will always point to the latest development version. If users do not like this they always have the option to override the default and pass in whatever version they would like instead.

For compatibility with older versions of Python

Ahsoka · 2020-09-20T20:59:11Z

@AutomatedTester Any updates on this PR?

Ahsoka · 2020-11-15T21:58:26Z

Hey @AutomatedTester, I just wanted to follow up again to see if there are any plans to merge this PR? If not, please let me know so I can stop bothering you and close this PR. 🙃

AutomatedTester · 2020-11-16T09:56:10Z

Hey @AutomatedTester, I just wanted to follow up again to see if there are any plans to merge this PR? If not, please let me know so I can stop bothering you and close this PR. 🙃

I need to find time to fix the build system for this PR. I am hoping soon

Ahsoka · 2020-11-16T18:23:38Z

Awesome, thank you so much for getting back to me. If there is anything I can do, please let me know! 😁

Ahsoka · 2022-02-13T20:58:59Z

Any updates on this?

Ahsoka added 3 commits August 22, 2020 00:07

Created the load_brython() method

f9a6c10

Used to load the necessary Javascript files to run Brython code.

Created the execute_brython() method

a58a378

This method allows you to execute Brython code just like the execute_script() method allows you to execute Javascript code.

Removed unnecessary call to decode() in the load_brython() method.

c6e34bb

Ahsoka added 10 commits August 22, 2020 12:45

Added docstring to load_brython()

48541bb

Added docstring to execute_brython()

43a5db3

Edited webdriver.py to comply with Lint Code Base recommendations

a30b51c

Edited loadBrython.js and runBrython.js to comply with Lint Code Base…

697f692

… recommendations

Escape single quotes instead of double quotes in execute_brython()

1a0cb4a

Changed script_tag to scriptTag in runBrython.js

fa09aab

Fixed over-indetation in webdriver.py

174d0e9

Fixed "Lines to Long" in start_session() and in __init__()

e923b11

Added an extra line between BrythonNotLoaded and UnknownMethodException

27cb60e

Minor edit to load_brython() docstring

52c51f7

Ahsoka force-pushed the brython branch from 7a8e08d to 95c7281 Compare August 22, 2020 20:59

Added a try finally to runBrython.js

10dba18

Ahsoka force-pushed the brython branch from 95c7281 to 10dba18 Compare August 22, 2020 21:01

Ahsoka added 3 commits August 22, 2020 14:19

Fixed an error in execute_brython() when using \n, \t, etc in script …

cb643ce

…argument

Removed unnecessary escaping of single quotes

e2e57c8

Ahsoka marked this pull request as ready for review August 23, 2020 00:04

AutomatedTester requested changes Aug 26, 2020

View reviewed changes

Ahsoka added 3 commits August 27, 2020 10:33

Added a timeout argument and updated docstring according to new changes

41f1449

Ahsoka added 3 commits August 27, 2020 15:45

Merge branch 'trunk' into brython

1bf2e08

Fixed typo in load_brython() docstring

27a7dd6

Moved runBrython.js and loadBrython.js into javascript/brython

8e672b4

Ahsoka force-pushed the brython branch from 1121760 to 224a772 Compare September 1, 2020 21:40

Changed f-string to .format when printing verbose

1e77848

For compatibility with older versions of Python

diemol added the C-py Python Bindings label Mar 29, 2021

github-actions bot added the Stale label Jan 30, 2022

github-actions bot closed this Feb 13, 2022

titusfortner added J-stale Applied to issues that become stale, and eventually closed. and removed Stale labels Mar 30, 2025

		@@ -0,0 +1,4 @@
		var script = document.createElement('script')

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Description

Examples

Example 1

Example 2

Types of changes

Checklist

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