JavaScript to Python Translator & JavaScript interpreter written in 100% pure Python🚀

>> add = js2py.eval_js('function add(a, b) {return a + b}') >>> add(1, 2) + 3 6 >>> add.constructor function Function() { [python code] } >>> js2py.require('underscore') 'function _(obj) { [python code] }'">

    >>> import js2py
    >>> js2py.eval_js('console.log( "Hello World!" )')
    'Hello World!'
    >>> add = js2py.eval_js('function add(a, b) {return a + b}')
    >>> add(1, 2) + 3
    6
    >>> add.constructor
    function Function() { [python code] }
    >>> js2py.require('underscore')
    'function _(obj) { [python code] }'

    >>> CryptoJS = js2py.require('crypto-js')
    >>> data = [{'id': 1}, {'id': 2}]
    >>> JSON = js2py.eval_js('JSON')
    >>> ciphertext = CryptoJS.AES.encrypt(JSON.stringify(data), 'secret key 123')
    >>> bytes  = CryptoJS.AES.decrypt(ciphertext.toString(), 'secret key 123')
    >>> decryptedData = JSON.parse(bytes.toString(CryptoJS.enc.Utf8)).to_list()
    >>> decryptedData
    [{u'id': 1}, {u'id': 2}]

    >>> js2py.eval_js6('let a = () => 11; a()')
    11

    # this will translate example.js to example.py
    >>> js2py.translate_file('example.js', 'example.py')
    # example.py can be now imported and used!
    >>> from example import example
    >>> example.someFunction()
    ...

>>> js2py.eval_js("Object.prototype.toString.call(Function('s', 'return s+arguments[1]')(new Date(), 7).__proto__)")
[object String]

pip install js2py

# Adding Python built-in sum to the JS context:
>>> context = js2py.EvalJs({'python_sum': sum})  
>>> js_code = '''
var a = 10
function f(x) {return x*x}
'''
>>> context.execute(js_code)
# Get value of variable a:
>>> context.a
10
# context.f behaves just like js function so you can supply more than 1 argument. '9'*'9' in javascript is 81.
>>> context.f('9', 0)  
81    
# context.f has all attributes of normal JavaScript object
>>> context.f.toString()
u'function f(x) { [python code] }'
>>> context.f.bind
function bind(thisArg) { [python code] }
# You can also add variables to the context:
>>> context.foo = [1,2,3]  # context.foo is now Js Array object and behaves just like javascript array!
>>> context.foo.push(4)  
4
>>> context.foo.to_list() # convert to python list
[1, 2, 3, 4]
# You can use Python objects that you put inside the context!
>>> context.eval('python_sum(new Array(1, 2, 3))')
6

>>> context = js2py.EvalJs(enable_require=True)
>>> context.eval("require('esprima').parse('var a = 1')")

>>> from js2py.internals import seval
>>> seval.eval_js_vm("try {throw 3+3} catch (e) {console.log(e)}", debug=True)
[LOAD_UNDEFINED(),
 JUMP(4,),
 LABEL(1,),
 LOAD_UNDEFINED(),
 POP(),
 LOAD_NUMBER(3.0,),
 LOAD_NUMBER(3.0,),
 BINARY_OP('+',),
 THROW(),
 NOP(),
 LABEL(2,),
 LOAD_UNDEFINED(),
 POP(),
 LOAD('console',),
 LOAD('e',),
 LOAD_N_TUPLE(1,),
 CALL_METHOD_DOT('log',),
 NOP(),
 LABEL(3,),
 LOAD_UNDEFINED(),
 NOP(),
 LABEL(4,),
 TRY_CATCH_FINALLY(1, 2, 'e', 3, False, 4)]

0 LOAD_UNDEFINED()
1 JUMP(4,)
18 TRY_CATCH_FINALLY(1, 2, 'e', 3, False, 4)
  ctx entry (from:2, to:9)
  2 LOAD_UNDEFINED()
  3 POP()
  4 LOAD_NUMBER(3.0,)
  5 LOAD_NUMBER(3.0,)
  6 BINARY_OP('+',)
  7 THROW()
  ctx exit (js errors)
  ctx entry (from:9, to:16)
  9 LOAD_UNDEFINED()
  10 POP()
  11 LOAD('console',)
  12 LOAD('e',)
  13 LOAD_N_TUPLE(1,)
  14 CALL_METHOD_DOT('log',)
6
  15 NOP()
  ctx exit (normal)

>>> js2py.eval_js('var a = "hello"; a')

Boolean -> bool
String -> unicode (str in Python 3)
Number -> float (or int/long if whole number)
undefined -> None
null -> None
OTHER -> JsObjectWrapper

>>> js = js2py.eval_js('d = {a:1, b:2}')
>>> js
{a: 1, b: 2}  
>>> type(js)
<class 'js2py.base.JsObjectWrapper'>
>>> js.a
1
>>> js['a']
1
>>> js.b = 20
>>> js
{a: 1, b: 20}  
>>> js['c'] = 30
>>> js.to_dict()
{u'a': 1, 'c': 30, u'b': 20}

>>> js2py.parse_js('var $ = 5')   
{
    "body": [
        {
            "declarations": [
                {
                    "id": {
                        "name": "$",
                        "type": "Identifier"
                    },
                    "init": {
                        "raw": "5",
                        "type": "Literal",
                        "value": 5
                    },
                    "type": "VariableDeclarator"
                }
            ],
            "kind": "var",
            "type": "VariableDeclaration"
        }
    ],
    "type": "Program"
}

>>> print(js2py.translate_js('var $ = 5'))
from js2py.pyjs import *
# setting scope
var = Scope( JS_BUILTINS )
set_global_object(var)

# Code follows:
var.registers(['$'])
var.put('$', Js(5.0))

>> js2py.eval_js(x) 18211 undefined">

>>> x = """pyimport urllib;
           var result = urllib.urlopen('https://www.google.com/').read();
           console.log(result.length)
        """
>>> js2py.eval_js(x)
18211
undefined