Introduction

PythonJS is a transpiler written in Python that converts Python into fast JavaScript. It can be run with regular Python, or fully self-hosted within NodeJS using Empythoned. PythonJS has been designed with speed and easy integration with existing JavaScript code in mind.

Using translator.py Without Installing

To simply convert your python script into javascript, git clone this repo, and use translator.py located in the "pythonjs" directory. You can give it a list of python files to translate at once. It will output the translation to stdout. The default output type is JavaScript.

Usage::

translator.py [--dart|--coffee|--lua] file.py

Example::

cd pythonjs
./translator.py myscript.py > myscript.js

Installing

npm install python-js

NodeJS Quick Example

var pythonjs = require('python-js');
var pycode = "a = []; a.append('hello'); a.append('world'); print(a)";
var jscode = pythonjs.translator.to_javascript( pycode );
eval( pythonjs.runtime.javascript + jscode );

JavaScript API

var pythonjs, output;
pythonjs = require('python-js');
output = pythonjs.translator.to_javascript( input );
output = pythonjs.translator.to_javascript_module( input );
output = pythonjs.translator.to_dart( input );
output = pythonjs.translator.to_coffee( input );
output = pythonjs.translator.to_lua( input );

pythonjs.runtime.javascript // runtime required by translator output

Example Projects

https://github.com/PythonJS/pythonjs-demo-server-nodejs

https://github.com/PythonJS/pypubjs

Speed

PythonJS gives you the option to optimize your program for speed with a new syntax for static typing, in some cases this results in code that is 20X faster. A variable can be statically typed as: int, float, long, str, list, or dict.
The translator then uses this type information to speed up runtime checks and method calls. In the example below x and y are typed as int.

def f(x,y):
	int x
	int y
	return x+y

The int type is accurate up to 53bits, if you need true 64bit integer math you can use the long type. Note using long requires the Long.js library.

You can further optimize your code with pythonjs.configure or special with statements that mark sections of the code as less dynamic.

N-Body benchmark

More benchmarks: Richards, n-body, Pystone, Fannkuch

GPU Translation

A Python typed subset can be translated to a GLSL fragment shader to speed up math on large arrays. GPU Documentation

Supported Features

####Language

classes
multiple inheritance
operator overloading
function and class decorators
getter/setter function decorators
list comprehensions
yield (generator functions)
regular and lambda functions
function calls with *args and **kwargs

####HTML DOM: for item in iterable NodeList FileList ClientRectList DOMSettableTokenList DOMStringList DataTransferItemList HTMLCollection HTMLAllCollection SVGElementInstanceList SVGNumberList SVGTransformList

####Operator Overloading

__getattr__
__getattribute__
__getitem__
__setitem__
__call__
__iter__
__add__
__mul__

####builtins

type
hasattr
getattr
setattr
issubclass
isinstance
dict
list
tuple
int
float
str
round
range
sum
len
map
filter
min
max
abs
ord
chr
open  (nodejs only)

####List

list.append
list.extend
list.remove
list.insert
list.index
list.count
list.pop
list.__len__
list.__contains__
list.__getitem__
list.__setitem__
list.__iter__
list.__getslice__

####Set

set.bisect
set.difference
set.intersection
set.issubset

####String

str.split
str.splitlines
str.strip
str.startswith
str.endswith
str.join
str.upper
str.lower
str.index
str.find
str.isdigit
str.format
str.__iter__
str.__getitem__
str.__len__
str.__getslice__

####Dict

dict.copy
dict.clear
dict.has_key
dict.update
dict.items
dict.keys
dict.get
dict.set
dict.pop
dict.values
dict.__contains__
dict.__iter__
dict.__len__
dict.__getitem__
dict.__setitem__

####Libraries

time.time
time.sleep
math.sin
math.cos
math.sqrt
array.array
os.path.dirname
bisect.bisect
random.random
threading.start_new_thread

#####Libraries (nodejs only) tempfile.gettempdir sys.stdin sys.stdout sys.stderr sys.argv sys.exit subprocess.Popen subprocess.call os.path.*

Regression Tests

The best way to see what features are currently supported with each of the backends is to run the automated regression tests in PythonJS/regtests. To test all the backends you need to install NodeJS, CoffeeScript, and Dart2JS. You should download the Dart SDK, and make sure that the executeable dart2js is in ~/dart-sdk/bin/

####Run Regression Tests

cd PythonJS/regtests
./run.py

Community

https://groups.google.com/forum/#!forum/pythonjs

irc freenode::

#pythonjs

akkolad/PythonJS