app.py

import toga
from toga.style import Pack
from toga.style.pack import COLUMN, ROW, CENTER

try:
    import js
except ModuleNotFoundError:
    js = None
try:
    from pyodide.ffi import create_proxy
except ModuleNotFoundError:
    pyodide = None

class HelloWorld(toga.App):
    def startup(self):
        main_box = toga.Box(style=Pack(direction=COLUMN))
        self.label = toga.Label(id="myLabel", text="Test App - Toga Web Testing")

        if js is not None:
            js.window.test_cmd = create_proxy(self.cmd_test)

        main_box.add(self.label)
        self.main_window = toga.MainWindow(title=self.formal_name)
        self.main_window.content = main_box
        self.main_window.show()
    
    def cmd_test(self, code):
        local_vars = {}
        try:
            exec(code, {'self': self, 'toga': toga}, local_vars)
            return local_vars.get("result", "No result")
        except Exception as e:
            return f'Error: {e}'
        
def main():
    return HelloWorld()