Run webpack on the fly

packme.js

#!/usr/bin/env node --harmony

// Fetch the Path, File System and Child Process modules
var Path = require('path');
var FS = require('fs');
var CP = require('child_process');

/**
 * The actual webpack config is stored within a function and then
 * extracted as a string as this preserves the regular expression
 * definitions whereas JSON.stringify does not.
 */
var webpackConfigFn = function(){
module.exports = {
  node: {
    console: true,
    fs: 'empty',
    net: 'empty',
    tls: 'empty'
  },

  entry: {},

  target: 'node',

  output: {
    path: './lib',
    filename: '[name].bundle.js',
    libraryTarget: 'commonjs2'
  },

  module: {
    loaders: [
      {
        test: /\.js$/i,
        exclude: /node_modules/,
        loader: 'babel-loader'
      },
      {
        test: /\.json$/i,
        loader: 'json-loader'
      }
    ]
  }
};
}

// This should be hardened; fetch the "first" param as a name
var targetName = process.argv[2];

// This should be hardened; fetch the "second" param as a path and resolve it
var targetPath = Path.resolve(process.argv[3]);

// Extract, modify and prepare the webpack configuration.
var codeString = webpackConfigFn
    .toString()
    .replace(/function \(\)\{/, '')
    .replace(/entry\: \{\}/, `entry: {${targetName}: '${targetPath}'}`);

// Get rid of the that last pesky closing brace from the function
codeString = codeString.substring(0, codeString.lastIndexOf('}'));

// Create a temporary directory (requires node >5; maybe just use /tmp?)
var tmpDir = FS.mkdtempSync('webpack', 'utf8');

// Create the path with the temporary directory
var tmpPath = Path.join(tmpDir, 'webpack.config.js');

// Write the webpack config to the temporary directory
FS.writeFileSync(tmpPath, codeString);

// Spit out the config so it can be seen visually
console.log('\033[1;4mWebpack Config\033[0m%s', codeString);

// Run webpack
CP.execSync(
  `webpack --config ${tmpPath}`,
  {
    cwd: __dirname,
    env: process.env,
    stdio: [
      process.stdin,
      process.stdout,
      process.stderr
    ]
  }
);

// Remove the config file
FS.unlinkSync(tmpPath);
FS.rmdirSync(tmpDir);