Exporting Objects from Python to JS

PyScriptPyodide

The PyScript (Pyodide) and PyScript(Micropython) version of this recipe are identical,

In the same way that pyscript.window can be used to import JavaScript objects into Python, the same object can be assigned to to create JavaScript objects from Python.

If we have some Python objects that we'd like to export as a JavaScript objects:

my_string = "This sure is a string"
my_list = [1,2,3]

def square(x):
    return x * x

class SimpleClass:
    def __init__(self, name):
        self.name = name

my_instance = SimpleClass("some name")

We can use the following Python syntax to create corresponding JavaScript objects:

from pyscript import window

window.a_string = my_string
window.a_list = [1,2,3]
window.square_func_from_python = square
window.some_instance = my_instance
window.some_class = SimpleClass

Notice that we can translate simple objects like strings, and increasingly more complex objects like lists, functions, class instances, and classes. Simple objects like ints, strs, and bools get converted to their corresponding JavaScript types; anything more complex appears in JavaScript as a proxy for the corresponding Python object. For a complete description of how objects are translated and proxied, see the Pyodide Documentation.

Tip

These examples work regardless of whether the code is run in the main thread or a worker thread - pyscript.window always references the global scope of the main thread. If you need access to the global scope of a worker thread, use import js, which is a proxy for the global scope of the thread the code is running in.

In the same way that the js pseudo-module can be used to import JavaScript objects into Python, the same 'module' can be assigned to to create JavaScript objects from Python.

If we have some Python objects that we'd like to export as a JavaScript objects:

my_string = "This sure is a string"
my_list = [1,2,3]

def square(x):
    return x * x

class SimpleClass:
    def __init__(self, name):
        self.name = name

my_instance = SimpleClass("some name")

We can use the following Python syntax to create corresponding JavaScript objects:

import js

js.a_string = my_string
js.a_list = my_list
js.square_func_from_python = square
js.some_instance = my_instance
js.some_class = SimpleClass

Notice that we can translate simple objects like strings, and increasingly more complex objects like lists, functions, class instances, and classes. Simple objects like ints, strs, and bools get converted to their corresponding JavaScript types; anything more complex appears in JavaScript as a proxy for the corresponding Python object. For a complete description of how objects are translated and proxied, see the Pyodide Documentation.