Babel compressor for jinja assets compiler (see https://github.com/jaysonsantos/jinja-assets-compressor/issues/51)

readme.md

Got to work with local node_modules installation.

1. At your app folder: npm install --save babel-cli babel-preset-es2015 babel-preset-react babel-preset-stage-0
2. manual run to test babel installation: node_modules/.bin/babel --presets=es2015,stage-0,react

input:

let a = 5; console.log(a);

after new empty line press Ctrl+D (EOF)

Expected output:

"use strict";

var a = 5;
console.log(a);

3. create babel_compressor.py from this gist: https://gist.github.com/d9k/651a7f926e85cbbfbf32631983529ea2
4. usage (at your web app entry point):

# change your.path.to.babel_compressor to actual path
from your.path.to.babel_compressor import BabelCompressor
from jac.config import Config as JacDefaultConfig

# . . . . .
# right before app initialization:

    # check paths with debugger!
    BabelCompressor.binary = os.path.abspath(os.path.join(os.path.dirname(__file__), '..', 'node_modules', '.bin', 'babel'))
    BabelCompressor.cwd_for_presets_search = os.path.abspath(os.path.join(os.path.dirname(__file__), '..'))
    jac_default_config = JacDefaultConfig()
    # get jinja2_env. In Pyramid you can get it this way:
    # `jinja2_env = pyramid_jinja2.get_jinja2_environment(config)`
    jinja2_env.compressor_classes = jac_default_config.get('compressor_classes')
    jinja2_env.compressor_classes['text/babel'] = BabelCompressor

5. at your jinja2 template code:

    {% compress 'js' %}
    <script type="text/babel">
        let a = 5;
        console.log(a);
    </script>
    {% endcompress %}

babel_compressor.py

# -*- coding: utf-8 -*-

import errno
import subprocess
from rjsmin import jsmin

from jac.compat import file, u, utf8_encode
from jac.exceptions import InvalidCompressorError


class BabelCompressor(object):
    """Compressor for text/babel mimetype (see https://babeljs.io/docs/setup/#installation).

    Uses the babel command line program to generate JavaScript, then
    uses rjsmin for minification.

    TODO does babel have it's own minification?
    """

    binary = 'babel'

    """
    to fix error Couldn't find preset "xxxxx" relative to directory ...
    define here any path inside the folder containing "node_modules" with babel executable
    """
    cwd_for_presets_search = None
    presets = ['es2015', 'stage-0', 'react']
    extra_args = []

    @classmethod
    def compile(cls, what, mimetype='text/babel', cwd=None, uri_cwd=None,
                debug=None):
        args = ['--presets=' + ",".join(cls.presets)]

        if cls.extra_args:
            args.extend(cls.extra_args)

        args.insert(0, cls.binary)

        try:
            handler = subprocess.Popen(args, stdout=subprocess.PIPE,
                                       stdin=subprocess.PIPE,
                                       stderr=subprocess.PIPE,
                                       cwd=cls.cwd_for_presets_search)
        except OSError as e:
            msg = '{0} encountered an error when executing {1}: {2}'.format(
                cls.__name__,
                cls.binary,
                u(e),
            )
            if e.errno == errno.ENOENT:
                msg += ' Make sure {0} is in your PATH.'.format(cls.binary)
            raise InvalidCompressorError(msg)

        if isinstance(what, file):
            what = what.read()

        (stdout, stderr) = handler.communicate(input=utf8_encode(what))
        stdout = u(stdout)

        if not debug:
            stdout = jsmin(stdout)

        if handler.returncode == 0:
            return stdout
        else:
            raise RuntimeError('Test this :S %s' % stderr)