pyduktape3 0.1.1

Yet another pyduktape fork written in Cython wrapped around duktape 3.0

pyduktape3

A Rewrite of pyduktape and pyduktape2 with extended features, typehinting support and cython importable data.

Documentation

Threading

It is possible to invoke Javascript code from multiple threads. Each thread will need to use its own embedded interpreter. Javascript objects returned to the Python environment will only be usable on the same thread that created them. The runtime always checks this condition automatically, and raises a DuktapeThreadError if it's violated.

Getting Started

Installation

To install from pypi::

pip install pyduktape3

To install the latest version from github::

pip install git+https://github.com/Vizonex/pyduktape3

Extra help

Typehints are now avalible since pyduktape3 now that a stub file (.pyi extension) is included so tools like vscode pyright should be able to pick up on typehints now. If this was a annoyance for you with the 2 original packages glad it's been gotten rid of now, it was the main reason behind this version's creation :)

Running Javascript code

To run Javascript code, you need to create an execution context and use the method eval_js::

import pyduktape3

context = pyduktape3.DuktapeContext()
context.eval_js("print(Duktape.version);")

Each execution context starts its own interpreter. Each context is independent, and tied to the Python thread that created it. Memory is automatically managed.

To evaluate external Javascript files, use eval_js_file::

// helloWorld.js
print('Hello, World!');

# in the Python interpreter
import pyduktape3

context = pyduktape3.DuktapeContext()
context.eval_js_file('helloWorld.js')

Pyduktape supports Javascript modules::

// js/helloWorld.js
exports.sayHello = function () {
    print('Hello, World!');
};

// js/main.js
var helloWorld = require('js/helloWorld');
helloWorld.sayHello();

# in the Python interpreter
import pyduktape3

context = pyduktape3.DuktapeContext()
context.eval_js_file('js/main')

The .js extension is automatically added if missing. Relative paths are relative to the current working directory, but you can change the base path using set_base_path::

# js/helloWorld.js
print('Hello, World!');

# in the Python interpreter
import pyduktape3

context = pyduktape3.DuktapeContext()
context.set_base_path('js')
context.eval_js_file('helloWorld')

Python and Javascript integration

You can use set_globals to set Javascript global variables::

import pyduktape3

def say_hello(to):
    print('Hello, {}!'.format(to))

context = pyduktape3.DuktapeContext()
context.set_globals(sayHello=say_hello, world='World')
context.eval_js("sayHello(world);")

You can use get_global to access Javascript global variables::

import pyduktape3

context = pyduktape3.DuktapeContext()
context.eval_js("var helloWorld = 'Hello, World!';")
print(context.get_global('helloWorld'))

eval_js returns the value of the last expression::

import pyduktape3

context = pyduktape3.DuktapeContext()
hello_world = context.eval_js("var helloWorld = 'Hello, World!'; helloWorld")
print(hello_world)

You can seamlessly use Python objects and functions within Javascript code. There are some limitations, though: any Python callable can only be used as a function, and other attributes cannot be accessed. Primitive types (int, float, string, None) are converted to equivalent Javascript primitives. The following code shows how to interact with a Python object from Javascript::

import pyduktape3

class Hello(object):
    def __init__(self, what):
        self.what = what

    def say(self):
        print('Hello, {}!'.format(self.what))

context = pyduktape3.DuktapeContext()
context.set_globals(Hello=Hello)
context.eval_js("var helloWorld = Hello('World'); helloWorld.say();")

In the same way, you can use Javascript objects in Python. You can use the special method new to instantiate an object::

import pyduktape3

context = pyduktape3.DuktapeContext()
Hello = context.eval_js("""
function Hello(what) {
    this.what = what;
}

Hello.prototype.say = function () {
    print('Hello, ' + this.what + '!');
};

Hello
""")

hello_world = Hello.new('World')
hello_world.say()

You can use Python lists and dicts from Javascript, and viceversa::

import pyduktape3

context = pyduktape3.DuktapeContext()
res = context.eval_js('[1, 2, 3]')

for item in res:
    print(item)

context.set_globals(lst=[4, 5, 6])
context.eval_js('for (var i = 0; i < lst.length; i++) { print(lst[i]); }')

res = context.eval_js('var x = {a: 1, b: 2}; x')
for key, val in res.items():
    print(key, '=', val)
res.c = 3
context.eval_js('print(x.c);')

context.set_globals(x=dict(a=1, b=2))
context.eval_js("""
var items = x.items();
for (var i = 0; i < items.length; i++) {
    print(items[i][0] + ' = ' + items[i][1]);
}
""")
context.set_globals(x=dict(a=1, b=2))
context.eval_js('for (var k in x) { print(k + " = " + x[k]); }')

Using in Cython

You can now extend this library and give it new meaning to your program and it's speed in execution::

cimport pyduktape3
cdef DuktapeContext context = pyduktape3.DuktapeContext()