[Python] Online Concatenate and Compress JavaScript Files

Online concatenate and compress JavaScript files via Python script.

Assume we want to concatenate and compress the following js files into a single js file.

tongwen_core.js
tongwen_table_ps2t.js
tongwen_table_pt2s.js
tongwen_table_s2t.js
tongwen_table_t2s.js
nanda.js

The tongwen_*.js are libraries and unchanged during our development. The only js file that we code with is nanda.js. We commit the above js files to GitHub, and write the following Python script to concatenate and compile the js files via online Closure Compiler [1] [2] [3] [4]. (put this py script in the same directory as js files)

#!/usr/bin/env python
# -*- coding: utf-8 -*- #

import httplib, urllib

allJS = ["nanda.js"]

def combineJS():
    js_code = ""
    for name in allJS:
        with open(name, 'r') as f:
            js_code += f.read()
    return js_code


def online_compile(js_code):
    # Define the parameters for the POST request and encode them in
    # a URL-safe format.

    params = urllib.urlencode([
        ('code_url', 'https://github.com/twnanda/twnanda/raw/master/theme/javascript/tongwen_core.js'),
        ('code_url', 'https://github.com/twnanda/twnanda/raw/master/theme/javascript/tongwen_table_ps2t.js'),
        ('code_url', 'https://github.com/twnanda/twnanda/raw/master/theme/javascript/tongwen_table_pt2s.js'),
        ('code_url', 'https://github.com/twnanda/twnanda/raw/master/theme/javascript/tongwen_table_s2t.js'),
        ('code_url', 'https://github.com/twnanda/twnanda/raw/master/theme/javascript/tongwen_table_t2s.js'),
        ('js_code', js_code),
        ('compilation_level', 'SIMPLE_OPTIMIZATIONS'),
        ('language', 'ECMASCRIPT5'),
        ('output_format', 'text'),
        ('output_info', 'compiled_code'),
    ])

    # Always use the following value for the Content-type header.
    headers = { "Content-type": "application/x-www-form-urlencoded" }
    conn = httplib.HTTPConnection('closure-compiler.appspot.com')
    conn.request('POST', '/compile', params, headers)
    response = conn.getresponse()
    print(response.read())
    conn.close()


if __name__ == "__main__":
    online_compile(combineJS())

Note that code_url is the URL of our raw files on GitHub, which tells the Closure Compiler to fetch files on GitHub instead of uploading them locally. The only file we POST to Closure Compiler service API is nanda.js, which we code with in our development.

Save above py script as compile.py and put in the same directory as js files. Run the script and save concatenated and compressed js as all.js by:

$ python compile > all.js

Tested on: Ubuntu Linux 15.10, Python 2.7.10.

References:

[1]	Closure Compiler service API

[2]	Getting Started with the API \| Closure Compiler \| Google Developers

[3]	Communicating with the Closure Compiler Service API \| Closure Compiler \| Google Developers

[4]	Compressing Files with the Closure Compiler Service API \| Closure Compiler \| Google Developers