LitElement Widget - minification

minify.js

const fs = require('fs');
const glob = require('glob');
const terser = require('terser');

// use glob in order to list all files we want to minify
const files = glob.sync('./lib/**.js');

files.forEach(filePath => {
  // get the unminified script content
  let data = fs.readFileSync(filePath, 'utf-8');
  
  /* replace import specifiers from unminified files
   * paths to their minified versions
   */
  data = data
    .replace(
      /from [',"]\.\/lit-element\.js[',"]/g,
      `from './lit-element.min.js'`
    )
    .replace(
      /from [',"]\.\/lit-html\.js[',"]/g,
      `from './lit-html.min.js'`
    );
  
  fs.writeFileSync(
    // add the .min.js extension
    filePath.replace(/\.js$/, '.min.js'),
    // minify using Terser API
    terser.minify(data, {
      // mandatory as we are minifying ES Modules here
      module: true,
      compress: {
        // compress twice for further compressed code
        passes: 2
      }
    }).code
  );
});