Combine ( merge ) multiple JS files into a single one. Build JS files using imports. Use build-time bindings from property files. Meant to be used in conjunction with a maven or ant build system.

build.py

#!/usr/bin/python
#
# Combine ( merge ) multiple JS files into a single one. Build JS files using imports.
# Use bindings from multiple property files.
#
# Use @import {file path} to import js files (paste into the current JS in the output).
# Pasting occurs at the site of the import statement.
# Use ${binding_name} to inject values from a property file when you build
#
# I chose simplicity and ease of understanding over complexity and featurefull-ness.
# I tried to limit memory usage by writing and closing immediately vs. storing as a variable,
# but I'm not familiar enough with python to know if I did any good.
#
# All JS which use @import are referred to as "templates"
# All files which get processed can use dynamic bindings ${property}
# If a file is @imported already, it won't be imported a second time; which means imports should
# be structured like modules and designed to be accessable from anywhere in the code.
#
# You can force a file to be imported more than once by using @!import instead of @import.
#
# Yes, @import-ing is recursive; so you can @import templates.
#
# A template may use up to two property files - a project level file, and a subclass property file.
# The project-level property file may include a ${property} found in subclass property files.
# Or of no subclass level property file is used, may use ${properties} in itself (recursive, 1 level).
# Unlike some frameworks, it doesn't keep recursing till all the ${properties} are bound; it only runs twice.
#
# Example:
#	template.js:
#		var value = "${some.binding}; oranges are ${desc}"
#	projectA.properties:
#		desc=delicious
#		some.binding="apples are ${desc}"
#	projectA.qa.properties:
#		desc=terrible
#		some.binding="apples are ${desc}"
#    When building with no -l argument, then the output will be:
#        var value = "apples are delicious; oranges are delicious"
#    When building with "-l qa" argument, the output is:
#        var value = "apples are delicious; oranges are terrible"
#
#
# You may need to install ConfigObj module:
#    sudo pip install configobj
#              OR
#    sudo easy_install configobj

import re, os, sys, getopt
from string import Template
try:
    from configobj import ConfigObj
except ImportError as e:
    print "\nError: Missing Import\nYou must install ConfigObject module (hint: pip install configobj or easy_install configobj)"
    sys.exit(2);

RE_IMPORTS = "/*\**\s*@(!?)import[\s/\*]+(\S*)"

desc = ''
project = ''
filename = ''
sourceDir = None
level = ''
propFilenameTop = ''
propFilenameProj = ''
outputfile = None

files = []
beenProcessed = {}

def getFileContent(filePath):
    try:
        f = open(filePath, 'r')
        if propFilenameTop:
            try:
                content = Template(Template(f.read()).safe_substitute(ConfigObj(propFilenameProj, file_error=True))).safe_substitute(ConfigObj(propFilenameTop, file_error=True),version=desc)
            except IOError as e:
                outputfile.close()
                print "\nERROR: File not found or cannot be opened: %s or %s,\n %s" % (propFilenameTop, propFilenameProj, e)
                sys.exit(2)
        else:
            content = f.read()
        f.close()
        return content
    except IOError as e:
        outputfile.close()
        print "\nERROR: File not found or cannot be opened: %s,\n %s" % (filePath, e)
        sys.exit(2)

def writeToFile(content):
    outputfile.write(content)
    outputfile.write("\n")

def process(filePath, modifier=None):
    filePath = os.path.join(sourceDir, filePath).strip()
    if filePath in beenProcessed and modifier != '!':
        if filePath not in files:
            print "\nERROR: Import loop. Imported script imports importing script."
            raise SystemExit
        return
    print "INFO: Importing file %s" % (filePath)
    beenProcessed[filePath] = 'true'
    content = getFileContent(filePath)
    last_i=0
    #example:   // @import subfolder/file.js
    for mob in re.finditer(RE_IMPORTS,content):
        if mob:
            writeToFile(content[last_i:mob.start()])
            last_i = mob.end()
            process(mob.group(2), mob.group(1))
    writeToFile(content[last_i:])
    files.append(filePath)

if __name__ == "__main__":
    outputfn = None
    errorstring = '\nERROR: Incorrect arguments: build.py -f <template_file_name> -s <source_dir> -p <property_filename> -d <versioning> -l <property_file_subclass> -o <output_file_name>'
    try:
        opts, args = getopt.getopt(sys.argv[1:],"f:p:d:l:s:o:")
    except getopt.GetoptError:
        print errorstring
        sys.exit(2)
    for opt, arg in opts:
        if opt == '-f':
            filename = arg
        elif opt == '-s':
            sourceDir = arg
        elif opt == '-o':
            outputfn = arg
        elif opt == '-p':
            project = arg
        elif opt == '-d':
            desc = arg
        elif opt == '-l':
            level = arg
        else:
            print errorstring
            sys.exit(2)
    if level:
        if level == 'prod':
            level = ''
        else:
            level = '.' + level
        if not project:
            print '\nERROR: requires -p argument (property filename minus extension) if level -l specified '
            sys.exit(2)
    if not filename:
        print '\nERROR: requires -f argument (file name of template), ' + filename
        sys.exit(2)
    if not sourceDir:
        sourceDir = './src'
        print 'INFO: No source directory provided, using default: ' + sourceDir
    if not outputfn:
        outputfn = './output.txt'
        print 'WARNING: No output file specified, using default: ' + outputfn
    if project:
        propertyDir = os.path.normpath(os.path.join(sourceDir, os.path.join("..", "build"))).strip()
        propFilenameTop = os.path.join(propertyDir, project+".properties").strip()
        propFilenameProj = os.path.join(propertyDir, project+level+".properties").strip()
        print "INFO: Using property files: %s and %s" % (propFilenameTop, propFilenameProj)

    try:
        outputfile = open(outputfn,'w')
    except IOError as e:
        print "\nERROR: Cannot open output file: %s , \n %s" % (outputfn, e)
        sys.exit(2)

    process(filename)
    outputfile.close()
    print "SUCCESS, output to %s" % (outputfn)